<Page>

                                                                     EXHIBIT 4.2

This instrument prepared by and
after recording should be mailed to:
Fred B. Jacobsen
Senior Counsel
The Peoples Gas Light and
  Coke Company
130 East Randolph Drive
Chicago, IL 60601


--------------------------------------------------------------------------------


                     THE PEOPLES GAS LIGHT AND COKE COMPANY

                                       TO

                         U.S. BANK NATIONAL ASSOCIATION

                                     TRUSTEE


                             SUPPLEMENTAL INDENTURE

                          DATED AS OF FEBRUARY 1, 2003

                FIRST AND REFUNDING MORTGAGE 5% BONDS, SERIES KK

--------------------------------------------------------------------------------

<Page>

                                                                     EXHIBIT 4.2

                                TABLE OF CONTENTS

<Table>
<Caption>
                                                                                             Page
                                                                                             ----
<S>                                                                                           <C>
Parties..................................................................................     1

Recitals
         Status of Mortgage..............................................................     1
         First and Refunding Mortgage Bonds
                  issued and outstanding.................................................     2
         Basis for issuance of $50,000,000
                  Series KK Bonds........................................................     2
         Reservation of right to amend the Mortgage......................................     2
         Form of Series KK registered bond without
                  coupons................................................................     3
         Supplemental Indenture authorized by
                  Directors..............................................................     9

                                           ARTICLE I

                            FIRST AND REFUNDING MORTGAGE 5% BONDS,
                                           SERIES KK

Sec. 1:  Designation, amount limited to
                  $50,000,000, maturity and
                           interest rate.................................................     11
                  Place and medium of interest and
                           principal payments............................................     11

Sec. 2:  Form of bonds...................................................................     11
                  Denominations of registered bonds
                           without coupons...............................................     12
                  Date of bonds..........................................................     12

Sec. 3:  Interdenominational exchanges of
                           registered bonds..............................................     12

Sec. 4:  Execution, authentication and issue of
                           Series KK Bonds...............................................     12

Sec. 5:  Redemption of Series KK Bonds
                           by Company....................................................     13
</Table>

                                        i
<Page>

<Table>
<Caption>
                                                                                             Page
                                                                                             ----
<S>                                                                                           <C>
Sec. 6:  Notice of Redemption............................................................     14

Sec. 7:  Legend on Series KK Bonds.......................................................     15

Sec. 8:  Definitions.....................................................................     15

Sec. 9: Payments, notices and actions due on
                  Saturdays, Sundays and holidays
                  to take place on next succeeding
                  Business Day...........................................................     16

Sec. 10:  Reservation of right to amend
                           the Mortgage..................................................     16

                                         ARTICLE II

                                  COVENANTS OF THE COMPANY

Sec. 1:  Company each year shall charge against income and place
         to credit of Depreciation Reserve Account the greater of
         $1,550,000 or 2.5% of the sum of the aggregate principal
         amount of all indebtedness of the Company secured by the
         Mortgage and liens superior to the Mortgage.....................................     18

Company after issuing any Series KK Bonds shall not request the Trustee to:

                  Authenticate any bonds under Mortgage pursuant to Sections 2,
                  4 or 5 of Article III or pay cash to the Company pursuant to
                  Section 6 of Article III on account of transactions effected
                  prior to January 1, 1951...............................................     19

                  Authenticate any series of bonds or pay any moneys to
                  Company on account of payment of any Refunding Mortgage 5%
                  bonds on or after January 1, 1944......................................     20
</Table>

                                     ii
<Page>

<Table>
<Caption>
                                                                                             Page
                                                                                             ----
         <S>                                                                                  <C>

         Company shall not request the Trustee to authenticate bonds of any
                  series or to pay to the Company any cash deposited with or
                  received by the Trustee, unless it delivers to the Trustee a
                  certificate signed by the President or an Executive or other
                  Vice President or Chief Financial Officer and Treasurer or
                  Assistant Treasurer containing
                  specified information..................................................     20

         Company shall not obtain authentication of
                  bonds or payment of cash in excess of
                  75% of amount shown on such certificate................................     22

         Explanation of terms--
                  Mortgage and Prior Lien Debt of Company................................     22
                  Net Earnings...........................................................     23
                  Permanent Property.....................................................     25
                  Original Cost..........................................................     25

         Company to furnish Trustee in connection with authentication of bonds
                  pursuant to Section 5 of Article III or payment of cash
                  pursuant to Section 6 of
                  Article III or of Article IX of the Mortgage:..........................     25

                  Opinion of counsel that
                  Company has acquired good title to
                  property...............................................................     25

                  Certificate of President or any
                  Executive or other Vice President
                  or Chief Financial Officer and also by
                  the Treasurer or an Assistant Treasurer certifying
                  that the property involved is
                  "permanent property"...................................................     26

         Company shall not hereafter issue any bonds
                  under any underlying mortgage..........................................     26
</Table>

                                   iii
<Page>

<Table>
<Caption>
                                                                                             Page
                                                                                             ----
<S>                                                                                           <C>
         Company not to request Trustee to authenticate bonds or to pay to it
                  cash on account of bonds purchased or redeemed through
                  operation of, or bonds deposited in, the sinking funds
                  provided for in supplemental indentures................................     26

         In event of acquisition of substantially all properties subject
                  to lien of Mortgage by federal, state or municipal authority,
                  Company shall be deemed to have requested Trustee to redeem
                  all bonds of all series under Mortgage.................................     26

         Classifying of "property replaced or retired"...................................     27

         If Company consolidates or merges with another corporation, successor must
                  assume payment of principal and interest on all bonds
                  outstanding under Mortgage.............................................     27

Sec. 2:  After-acquired property shall be
                           subject to lien of Mortgage...................................     27

Sec. 3:  Company to furnish certificates,
                           mortgages, deeds, opinions of
                           counsel to Trustee within sixty
                           (60) days after acquiring land,
                           plants or interests in lands or
                           plants the aggregate cost of
                           which shall equal or
                           exceed $500,000...............................................     28

Sec. 4:  Company covenants that upon cancellation
                           of any "prior lien" it shall cause
                           all cash or obligations held by
                           trustee of such "prior lien" to be
                           paid over to Trustee..........................................     30
</Table>

                                       iv
<Page>

<Table>
<Caption>
                                                                                             PAGE
                                                                                             ----
<S>                                                                                           <C>
                                        ARTICLE III

                                       MISCELLANEOUS

Sec. 1:  Trustee's Acceptance............................................................     30

Sec. 2:  Supplemental Indenture executed
                           pursuant to Article XVI of Mortgage...........................     31

Sec. 3:  All covenants and conditions by or
                           on behalf of Company to bind its
                           successors and assigns........................................     31

Sec. 4:  Supplemental Indenture to become
                           effective only from time of its
                           actual execution and delivery
                           by the Company and Trustee....................................     31

Execution in counterparts................................................................     31
Attestation clause.......................................................................     32
Signatures...............................................................................     32
Acknowledgment by Company................................................................     33
Acknowledgment by Trustee................................................................     34
</Table>
                                        v
<Page>

     This Supplemental Indenture, dated as of February 1, 2003, made and entered
into by and between THE PEOPLES GAS LIGHT AND COKE COMPANY, a corporation
organized and existing under the laws of the State of Illinois (hereinafter
called the "Company") and U.S. Bank National Association (hereinafter called the
"Trustee"), a corporation organized and existing under laws of the United States
of America and successor to Illinois Merchants Trust Company, as trustee under
the indenture of Chicago By-Product Coke Company to said Illinois Merchants
Trust Company, as trustee, dated January 2, 1926,

                                   WITNESSETH:

     WHEREAS, Chicago By-Product Coke Company, a corporation organized and
existing under the laws of the State of Delaware, heretofore gave its mortgage
in the form of an indenture (hereinafter called the "Original Mortgage") to
Illinois Merchants Trust Company, as trustee, under date of the second day of
January, 1926; and

     WHEREAS, the Company executed and delivered to said Illinois Merchants
Trust Company, as trustee under the Original Mortgage, an indenture bearing date
the first day of March, 1928, whereby, among other things, the Company assumed
and agreed to pay the principal and interest of all bonds issued or to be issued
under the Original Mortgage and secured thereby, and to perform and fulfill all
of the terms, covenants, and conditions of the Original Mortgage binding upon
said Chicago By-Product Coke Company, and in and by said indenture the Company
subjected to the lien of the Original Mortgage, subject to the existing liens
permitted by Section 2 of Article XIV of the Original Mortgage but with
statements required by said Section 2 with regard to such existing liens, all of
the property then owned by the Company or thereafter acquired by it (excepting
such of its property as the Company was by said Section 2 of Article XIV of the
Original Mortgage expressly authorized to reserve from the lien of the Original
Mortgage); and

     WHEREAS, by virtue of all the things done as in the next preceding
paragraph recited, the Company has become the successor corporation under the
Original Mortgage, subject to all the terms, conditions and restrictions
thereof; and

     WHEREAS, thereafter the Company has made, executed and delivered other
indentures supplemental to the Original Mortgage, of which the indentures
supplemental to the Original Mortgage delivered to U.S. Bank National
Association, as Trustee, successor to Illinois Merchants Trust Company, as
Trustee under the Original Mortgage, dated, respectively, May 20, 1936, March
10, 1950, as of June 1, 1951, as of August 15, 1967, as of September 15, 1970,
as of March 1, 1985, as of April 1, 1993, as of December 1, 1993, as of December
1, 1993, as of June 1, 1995, as of March 1, 2000, as of March 1, 2000, as of
March 1, 2000 and as of March 1, 2000 are wholly or partially in full force and
effect (said Original Mortgage, and said Indenture dated March 1, 1928, as so
supplemented and amended, being collectively called the "Mortgage", and said
Mortgage, as supplemented by this Supplemental Indenture, being collectively
called the "Mortgage as supplemented"); and

                                        1
<Page>

     WHEREAS, all bonds which have heretofore been issued and outstanding under
the Mortgage have been retired and cancelled, except that as of December 31,
2002, there were bonds of the following series outstanding in the aggregate
principal amounts indicated below:

<Table>
<Caption>
                                                                Aggregate
Bonds                          Due Date                      Principal Amount
-----                          --------                      ----------------
<S>                            <C>                             <C>
Series X                       March 1, 2015                   $ 50,000,000
Series CC                      May 1, 2003                     $ 75,000,000
Series DD                      December 1, 2023                $ 75,000,000
Series EE                      December 1, 2023                $ 27,000,000
Series FF                      June 1, 2025                    $ 50,000,000
Series GG                      March 1, 2030                   $ 50,000,000
Series HH                      March 1, 2030                   $ 50,000,000
Series II                      March 1, 2030                   $ 37,500,000
Series JJ                      March 1, 2030                   $ 37,500,000
</Table>

; and

     WHEREAS, it is provided in Article III of the Mortgage that bonds of any
series may from time to time be issued by the Company under the Mortgage in a
principal amount equal to 75% of expenditures made for the acquisition of any
permanent property as defined in the mortgage or upon the deposit of cash with
the Trustee equal to the aggregate principal amount of bonds whose
authentication and delivery is then applied for; and

     WHEREAS, the Company has duly determined to create an additional series of
its bonds to be issued under the Mortgage as supplemented designated "The
Peoples Gas Light and Coke Company First and Refunding Mortgage 5% Bonds, Series
KK" (herein sometimes referred to as "bonds of Series KK") and to issue an
aggregate of $50,000,000 principal amount of said bonds all of which bonds shall
be fully registered without coupons; and

     WHEREAS, the Company desires to reserve the right to amend the Mortgage
without any consent or other action by holders of the bonds of Series KK or any
subsequent series, to provide that the Mortgage, the rights and obligations of
the Company and the rights of the bondholders may be modified with the consent
of the holders of not less than 60% in aggregate principal amount of the bonds
adversely affected; provided, however, that no modification shall (1) extend the
time, or reduce the amount, of any payment on any bond, without the consent of
the holder of each bond so affected, (2) permit the creation of any lien, not
otherwise permitted, prior to or on a parity with the lien of the Mortgage,
without the consent of the holders of all bonds then outstanding, or (3) reduce
the above percentage of the aggregate principal amount of bonds the holders of
which are required to approve any such modification without the

                                        2
<Page>

consent of the holders of all bonds then outstanding; and

     WHEREAS, the form of registered bond of Series KK and the form of the
Trustee's Certificate to appear on all bonds of Series KK shall be substantially
as follows:

               (Form of Series KK Registered Bond Without Coupons)

  No. R ____________                                     $______________

                     THE PEOPLES GAS LIGHT AND COKE COMPANY

                      FIRST AND REFUNDING MORTGAGE 5% BOND,

                                    SERIES KK

                              DUE February 1, 2033

  THE PEOPLES GAS LIGHT AND COKE COMPANY, an Illinois corporation (hereinafter
called the "Company"), for value received, hereby promises to pay to ___________
_________________, or registered assigns on February 1, 2033, unless this Bond
shall have been called for redemption and payment of the redemption price shall
have been duly made or provided for in accordance with the hereinafter described
Mortgage, the principal sum of _________________ Dollars ($__________), and to
pay interest on the balance of said principal sum from time to time remaining
unpaid from the February 1 or August 1 to which interest has been paid next
preceding the date of authentication of this Bond, unless this bond is
authenticated on a February 1 or August 1 to which interest has been paid, in
which event this Bond shall bear interest from such February 1 or August 1, or
unless no interest has been paid on this Bond, in which event this Bond shall
bear interest from the date hereof, at the rate of five percent (5%) per annum
(calculated on the basis of a year of 360 days consisting of twelve 30-day
months), payable at or before 9:00 a.m., Chicago time, on February 1 and August
1 of each year, commencing August 1, 2003 until payment in full of such
principal sum. Interest shall also accrue on any overdue principal, premium, if
any, and (to the extent that such interest shall be legally enforceable) on any
overdue installment of interest until paid at the same rate per annum. The
interest so payable on any interest payment date will, subject to certain
exceptions provided in the Mortgage, be paid to the person who is the registered
owner of this Bond at the close of business on the applicable record date next
preceding such interest payment date. Principal of, premium, if any, and
interest on this Bond shall be payable in lawful money of the United States of
America at the principal corporate office or agency of the Company in Chicago,
Illinois.

     This Bond is one of the First and Refunding Mortgage Bonds of the Company,

                                        3
<Page>

all issued and to be issued in series, from time to time, under and in
accordance with and, irrespective of the time of issue or of the series in which
issued or the designation thereof, equally secured by an Indenture, dated the
second day of January, 1926, executed by Chicago By-Product Coke Company, a
Delaware corporation, to Illinois Merchants Trust Company, as trustee, and
recorded on January 19, 1926, as Document No. 9154395 in Book 22219 of Records,
at page 283, in the Recorder's Office of Cook County, Illinois, which Indenture
was assumed by the Company as a successor corporation, as defined therein, by an
indenture, dated the first day of March, 1928, executed by the Company to said
trustee, and recorded on April 7, 1928, as Document No. 9980547 in Book 25701 of
Records, at page 599, in the Recorder's Office of Cook County, Illinois, and has
heretofore been, and from time to time hereafter may be, amended and
supplemented by indentures supplemental thereto, including the Supplemental
Indenture dated as of February 1, 2003 relating to the hereinafter described
Series KK Bonds (the "Supplemental Indenture"). Unless otherwise defined herein,
all capitalized terms used herein shall have the meanings ascribed thereto in
the Supplemental Indenture. The word "Mortgage", as used in this Bond, shall
mean said Indenture, as amended and supplemented from time to time by indentures
supplemental thereto, including the Supplemental Indenture. The word "Company",
as used in this Bond, shall be construed to include any successor corporation,
as defined in the Mortgage. The word "Trustee", as used in this Bond, shall be
construed to mean and include U.S. Bank National Association (successor to
Illinois Merchants Trust Company), as trustee under the Mortgage, and any
successor trustee thereunder. Reference is hereby made to the Mortgage and all
indentures supplemental thereto for a description of the property mortgaged and
pledged (except that certain parcels described in the Mortgage and in said
supplemental indentures have been released from the lien of the Mortgage
pursuant to the terms thereof), the nature and extent of the security and the
terms and conditions governing the issuance and security of the bonds issued or
to be issued under the Mortgage. As provided in the Mortgage, the bonds may be
for various principal sums, are issuable in series, may bear interest at
different rates and may otherwise vary as provided therein. This Bond is one of
the series of such First and Refunding Mortgage Bonds designated as "The Peoples
Gas Light and Coke Company First and Refunding Mortgage 5% Bonds, Series KK",
hereinafter called the "Series KK Bonds".

     The Series KK Bonds shall be deliverable in the form of registered Bonds
without coupons in the denominations of $5,000 and any integral multiple
thereof.

     As more fully described in the Supplemental Indenture, the Company reserves
the right, without any consent or other action by holders of the Series KK Bonds
or the bonds of any subsequent series, to amend the Mortgage to provide that the
Mortgage, the rights and obligations of the Company and the rights of the
bondholders may be modified with the consent of the holders of not less than 60%
in aggregate principal amount of the bonds adversely affected; provided,
however, that no modification shall (1) extend the time, or reduce the amount,
of any payment on any bond, without the consent of the holder of each bond so
affected, (2) permit the creation of any lien, not otherwise permitted, prior to
or on a parity with the lien of the Mortgage, without the

                                        4
<Page>

consent of the holders of all bonds then outstanding, or (3) reduce the above
percentage of the principal amount of bonds the holders of which are required to
approve any such modification without the consent of the holders of all bonds
then outstanding.

     The Series KK Bonds are subject to optional redemption prior to maturity by
the Company on or after February 1, 2013, in whole at any time or in part on any
interest payment date, at the redemption price of 100% of the principal amount
thereof plus accrued interest, if any, to the redemption date.

     The Series KK Bonds are subject to optional redemption by the Company, in
whole but not in part, at any time, at a redemption price of 100% of the
principal amount thereof, plus accrued interest, if any, to the redemption date,
upon the occurrence of certain events described in the Supplemental Indenture
(relating to unreasonable burdens or excessive liabilities imposed upon the
Company; changes in the economic availability of raw materials, operating
supplies, fuel or other energy sources or supplies or technological or other
changes rendering the Project uneconomic; court order or decree preventing
operations at the Project or rendering the continuation of the Project's
operations economically unfeasible).

     All of the outstanding Series KK Bonds may be redeemed at any time by the
Company, by the payment of the principal amount thereof and accrued interest
thereon to the date of redemption, without the payment of any premium, in the
event of the acquisition by any federal, state or municipal authority of any
substantial portion (which shall be not less than one-third as determined by
book values) of the income-producing properties of the Company which are subject
to the lien of the Mortgage.

     All of the outstanding bonds under the Mortgage shall be redeemed by the
Company by the payment of the respective applicable redemption price or prices
and accrued interest thereon to the date of redemption, without the payment of
any premium, in the event of the acquisition by any federal, state or municipal
authority of all or substantially all of the income-producing properties of the
Company which are subject to the lien of the Mortgage.

     All of the outstanding Series KK Bonds shall be redeemed by the Company not
more than sixty (60) days after the Trustee receives written notice from the
Revenue Bond Trustee stating that the principal on the Revenue Bonds has been
declared to be immediately due and payable as a result of an event of default
under the Revenue Bond Indenture (as defined in the Mortgage). The redemption
price for any such redemption shall be 100% of the principal amount of the
Series KK Bonds to be redeemed, plus interest thereon accrued to the date fixed
for redemption.

     Series KK Bonds are also subject to mandatory redemption at any time, in
whole (or in part as hereinafter provided), at 100% of the principal amount
thereof, plus accrued interest, if any, to the redemption date, in the event
that it is finally determined by the Internal Revenue Service or by a court of
competent jurisdiction that, as a result of the failure by the Company to
observe any covenant, agreement or representation in

                                        5
<Page>

that certain Loan Agreement dated as of February 1, 2003 between the Company and
the Illinois Development Finance Authority, the interest payable on the Revenue
Bonds is includable for federal income tax purposes in the gross income of any
owner thereof, other than an owner who is a "substantial user" of the Project or
a "related person" of such substantial user, as provided in Section 147(a) of
the Internal Revenue Code of 1986, as amended (the "Code"), and the applicable
regulations thereunder. Any such determination will not be considered final for
this purpose unless the Company has been given written notice and, if it so
desires, has been afforded the opportunity to contest the same, either directly
or in the name of any owner of a Revenue Bond, and until the conclusion of any
appellate review, if sought. The Series KK Bonds shall be redeemed in whole
after such determination unless redemption of a portion of the Revenue Bonds
outstanding would have the result that interest payable on the Revenue Bonds
remaining outstanding after such redemption would not be includable for federal
income tax purposes in the gross income of any owner of the Revenue Bonds (other
than an owner who is a "substantial user" of the Project or a "related person"
of such substantial user within the meaning of Section 147(a) of the Code), and
in such event the Series KK Bonds shall be redeemed in such amount as to
accomplish that result.

     Notice of any redemption of the Series KK Bonds shall be given by mailing
by first-class mail, postage prepaid, at least thirty (30) days and not more
than sixty (60) days prior to the redemption date, to the holders of all such
bonds to be redeemed at their last addresses that shall appear upon the registry
book, all as more fully provided in the Mortgage. Notice of redemption having
been duly given, the bonds called for redemption shall become due and payable
upon the redemption date and, if the redemption price shall have been deposited
with the Trustee, interest thereon shall cease to accrue on and after the
redemption date, and whenever the redemption price thereof shall have been
deposited with the Trustee and notice of redemption shall have been duly given
or provision therefore made, such bonds shall no longer be entitled to any lien
or benefit of the Mortgage.

     In case of certain events of default specified in the Mortgage, the
principal of all bonds issued and outstanding thereunder may be declared or may
become due and payable in the manner and with the effect provided in the
Mortgage.

     No recourse shall be had for the payment of the principal of or interest on
this Bond, or for any claim based hereon, or otherwise in respect hereof or of
the Mortgage, to or against any incorporator, stockholder, director or officer,
past, present or future, of the Company, either directly or through the Company,
under any constitution or statute or rule of law or by the enforcement of any
assessment or penalty or otherwise, all such liability of incorporators,
stockholders, directors and officers being released by the holder hereof by the
acceptance of this Bond, and being likewise waived and released by the terms of
the Mortgage.

     This Bond is transferable by the registered holder hereof in person or by a
duly authorized attorney at the office or agency of the Company in the City of
Chicago, State of Illinois, upon surrender and cancellation of this Bond, and
thereupon a new registered

                                        6
<Page>

bond or bonds, without coupons, of the same series and for the same aggregate
principal amount will be issued to the transferee in exchange herefor. In the
manner provided in the Mortgage, registered Bonds without coupons of this series
may, at the option of the registered owner and upon surrender at said office or
agency of the Company, be exchanged for registered Bonds without coupons of this
series of the same aggregate principal amount of other authorized denominations.
Notwithstanding the foregoing, this Bond may not be sold, transferred, pledged
or hypothecated except as required to effect assignment to the Revenue Bond
Trustee and to any successor trustee.

     The Company and the Trustee and any paying agent may deem and treat the
person in whose name this Bond is registered as the absolute owner hereof for
the purpose of receiving payment and for all other purposes and neither the
Company nor the Trustee nor any paying agent shall be affected by any notice to
the contrary.

     This Bond shall not be entitled to any security or benefit under the
Mortgage, and shall not become valid or obligatory for any purpose, until this
Bond shall have been authenticated by the execution of the certificate, hereon
endorsed, by the Trustee or its successor in trust under the Mortgage.

                                        7
<Page>

     IN WITNESS WHEREOF, the Company has caused this Bond to be executed in its
name by its President, Executive Vice President, Chief Financial Officer,
Treasurer or a Vice President manually or in facsimile, and has caused its
corporate seal manually or in facsimile to be hereto affixed, attested by the
manual or facsimile signature of its Secretary or of an Assistant Secretary.

   Dated:
          --------------

          THE PEOPLES GAS LIGHT AND COKE COMPANY

             By
                ----------------------------
                        President

   Attest:



-------------------------
          Secretary


                         (Form of Trustee's Certificate)

  This bond is one of the bonds of the series designated, referred to and
described in the within-mentioned Mortgage.


                         U.S. BANK NATIONAL ASSOCIATION

           By
               ----------------------------
                    Authorized Officer.

                                        8
<Page>

                                   ASSIGNMENT

For value received, the undersigned hereby sell(s) and transfer(s) unto:

PLEASE INSERT SOCIAL SECURITY OR OTHER
IDENTIFYING NUMBER OF ASSIGNEE:  _____________________

______________________________________________________

______________________________________________________
(Please print or typewrite name and address, including zip code of assignee)

the within Bond and all rights thereunder, hereby irrevocably constituting and
appointing _____________ Attorney to transfer said Note on the books of the
Trustee with full power of substitution in the premises.

Dated:
       ------------------                    -----------------------------
                                                 Notice:  The  signature  to
                                             this  Assignment  must  correspond
                                             with the name as written upon the
                                             face of the within instrument in
                                             every particular, without
                                             alteration or enlargement, or any
                                             changes whatever.

and

     WHEREAS, all acts and things necessary to make the bonds of Series KK, when
authenticated by the Trustee and issued as in the Mortgage and in this
Supplemental Indenture provided, the valid, binding and legal obligations of the
Company, entitled in all respects to the security of the Mortgage, have been
done and performed and the creation, execution and delivery of this Supplemental
Indenture have in all respects been duly authorized by a resolution adopted by
the Board of Directors of the Company; and

     WHEREAS, the Company has requested the Trustee, pursuant to the provisions
of Article XVI of the Mortgage, to enter into this Supplemental Indenture for
the purpose of supplementing the Mortgage as herein provided;

     NOW, THEREFORE, in consideration of the premises and of the sum of One
Dollar ($1.00) duly paid by the Trustee to the Company and for other good and
valuable considerations, the receipt whereof is hereby acknowledged, the parties
hereto agree as follows:

                                        9
<Page>

       DESCRIPTION OF CERTAIN PROPERTY SUBJECT TO THE LIEN OF THE MORTGAGE

     The Company hereby mortgages and conveys unto the Trustee, its successor or
successors in trust, the property described in Schedule A hereto attached and
expressly made a part hereof.

     TO HAVE AND TO HOLD all of said property hereby conveyed and mortgaged or
intended to be conveyed and mortgaged, together with the rents, issues and
profits thereof, unto the Trustee, and its successor or successors in trust and
their assigns in trust, under the and subject to all of the terms, conditions
and provisions of the Mortgage (as the Mortgage is defined herein) and of this
Supplemental Indenture as fully and in all respects as if said property had
originally been described in said Mortgage.

     Subject, however, to the reservations, exceptions, limitations and
restrictions contained in the several deeds, leases, servitudes, contracts or
other instruments through which the Company acquired and/or claimed title to
and/or enjoys the use of the mortgaged property, and subject also to any
mortgages or easements existing or placed on any of said property at the time of
its acquisition, liens, for taxes and assessments not due or, if due, in the
course of contests, judgments in the course of appeal or otherwise in contest
and secured by sufficient bond, liens arising out of proceedings in court in the
course of contests and undetermined liens or charges (if any) incidental to
construction, and subject also to such servitude, easements, rights and
privileges in, over, on or through said property as may have been granted by the
Company to other persons prior to the date of this Supplemental Indenture.

     BUT IN TRUST, NEVERTHELESS, for the equal and proportionate benefit and
security of the holders of all bonds and interest coupons now or hereafter
issued under the Mortgage and for the enforcement of and payment of said bonds
and coupons when payable and the performance of and compliance with the
covenants and conditions of the Mortgage without any preference, distinction or
priority as to lien or otherwise of any bond or bonds over others by reason of
difference in time of the actual issue, sale or negotiation thereof; but so that
each and every bond now or hereafter issued under the Mortgage shall have the
same lien so that the interest and principal of any and all of such bonds shall,
subject to the terms of the Mortgage, be equally and proportionately secured
thereby, as if they had been made, executed, delivered, sold and negotiated
simultaneously with the execution thereof.

     UPON CONDITION that, until the happening of an event of default as provided
in the Mortgage, the Company shall be suffered and permitted to possess, use and
enjoy the property, rights, privileges and franchises conveyed herein and to
receive and use the rents, issues, income, revenues, earnings and profits
thereof.

     IT IS HEREBY COVENANTED, DECLARED AND AGREED by and between the Company and
the Trustee, and its successor or successors in trust, as follows:

                                       10
<Page>

                                    ARTICLE I

                     FIRST AND REFUNDING MORTGAGE 5% BONDS,

                                    SERIES KK

     SECTION 1. A new series of bonds of the Company shall be issued under and
secured by the Mortgage as supplemented, which shall be designated as the
Company's "First and Refunding Mortgage 5% Bonds, Series KK". The aggregate
principal amount of bonds of Series KK which may be executed by the Company and
authenticated by the Trustee shall be limited to $50,000,000 (exclusive of bonds
authenticated and delivered upon interdenominational or other exchanges and
transfers pursuant to Section 3 of Article I hereof and Sections 2, 5, 11 and 12
of Article I of the Original Mortgage and delivered pursuant to Section 3 of
Article VI of the Original Mortgage as the same may relate to fully registered
bonds). Bonds of Series KK all shall be registered bonds without coupons, and
shall be due and payable February 1, 2033. All bonds of Series KK shall bear
interest from the date thereof, payable at or before 9:00 o'clock a.m. Chicago
time on the first day of February and the first day of August in each year,
commencing August 1, 2003, until the principal thereof shall have become due and
payable, at the rate of 5% per annum, and on any overdue principal and (to the
extent that payment of such interest is enforceable under the applicable law) on
any overdue installment of interest at the same rate per annum, and shall be
payable both as to principal and interest, and as to premium, if any, in coin or
currency of the United States of America which at the time of payment is legal
tender for the payment of public and private debts, at the office or agency of
the Company in the City of Chicago, Illinois.

     So long as there is no existing default in the payment of interest on the
bonds of Series KK, the interest payable on any interest payment date shall be
to the person in whose name any bond of Series KK is registered at the close of
business on any record date with respect to any payment date, and such person
shall be entitled to receive the interest payable on such interest payment date
notwithstanding any transfer or exchange of such bond of Series KK subsequent to
the record date and on or prior to such interest payment date, except as and to
the extent the Company shall default in the payment of the interest due on such
interest payment date, in which case such defaulted interest shall be paid to
the person in whose name such bond of Series KK is registered at the close of
business on a subsequent record date, which shall not be less than five (5) days
prior to the date of payment of such defaulted interest established by notice
given by mail by or on behalf of the Company to the person in whose name such
bond of Series KK is then registered and to the Trustee not less than ten (10)
days preceding such subsequent record date.

     As used in this Section I, the term "default in the payment of interest"
means failure to pay interest on the applicable interest payment date
disregarding any period of grace permitted by Article X of the Mortgage.

     SECTION 2. Bonds of Series KK may be issued only as registered bonds
without coupons (hereinafter sometimes referred to as "registered bonds"), and
they shall

                                       11
<Page>

be substantially in the form hereinbefore recited. They shall be issuable in
denominations which shall be multiples of $5,000 and any integral multiple
thereof and the execution by the Company of any bond of Series KK shall evidence
conclusively the due authorization of the denomination of such bond. Each
registered bond of Series KK shall be dated as of the date of the interest
payment date on which interest was paid on other bonds of said Series next
preceding the date of issue of such registered bond, except that (i) so long as
there is no existing default in the payment of interest upon the bonds of Series
KK, any bond of Series KK issued after the close of business on any record date
with respect to any interest payment date and prior to such interest payment
date, shall be dated as of such interest payment date, and (ii) any bond of
Series KK issued on an interest payment date on which interest on other bonds of
Series KK was paid shall be dated as of the date of issue and (iii) any bond of
Series KK issued before the initial interest payment date, shall be dated
February 6, 2003, the date of commencement of the first interest period for the
bonds of Series KK, unless (i) above is applicable.

     The registered owner of any bond of Series KK dated as of an interest
payment date as provided in (i) above shall, if the Company shall default in the
payment of interest due on such interest payment date and such default shall be
continuing, be entitled to exchange such bond for a bond or bonds of Series KK
of the same aggregate principal amount dated as of the interest payment date
next preceding the interest payment date first mentioned in this sentence, or,
if the Company shall default in the payment of interest on the first interest
payment date for bonds of Series KK, such owner shall be entitled to exchange
such bond for a bond or bonds of Series KK of the same aggregate principal
amount dated February 6, 2003. If the Trustee shall have knowledge at any time
that any registered owner of a bond of Series KK shall be entitled by the
provision of the next preceding sentence to exchange such bond, the Trustee
shall within thirty (30) days mail to such owner at the address of such owner
appearing upon the registry book, a notice informing such owner that such owner
has such right of exchange.

     SECTION 3. In the manner prescribed in the Mortgage, the holder of a
registered bond or bonds of Series KK may, at the office or agency of the
Company in the City of Chicago, State of Illinois, surrender such bond or bonds
in exchange for a like aggregate principal amount of one or more registered
bonds of Series KK of any authorized denomination or denominations.

     No charge will be made by the Company to the registered owner of a bond of
Series KK for the transfer thereof or for the exchange thereof for bonds of
Series KK of other authorized denominations, except, in the case of transfer, a
charge sufficient to reimburse the Company for any stamp or other tax or
governmental charge required to be paid by the Company or the Trustee.

     SECTION 4. All bonds of Series KK shall be executed on behalf of the
Company by the manual or facsimile signature of its President or the Executive
Vice President or the Chief Financial Officer or the Treasurer or a Vice
President and shall

                                       12
<Page>

have affixed thereon the manual or facsimile seal of the Company attested by the
manual or facsimile signature of its Secretary or one of its Assistant
Secretaries and be authenticated by the execution by the Trustee of the
certificate endorsed on said bonds, and said bonds shall be issued from time to
time, as the Board of Directors of the Company may determine, but in accordance
with the terms, provisions, conditions and restrictions set forth in the
Mortgage and in this Supplemental Indenture. The definitive bonds of Series KK
may be issued in typewritten or printed form or otherwise as provided in the
Mortgage.

     SECTION 5. (a) The bonds of Series KK are subject to optional redemption by
the Company, in whole but not in part, at any time, at a redemption price of
100% of the principal amount thereof plus accrued interest, if any, to the
redemption date, if any of the following shall have occurred and if within one
hundred and eighty (180) days following said occurrence the Company files
written notice with the Illinois Finance Development Authority and the Revenue
Bond Trustee and directs that the Revenue Bonds are to be redeemed:

          (i)    if, in the Company's reasonable judgment, unreasonable burdens
     or excessive liabilities shall, have been imposed upon the Illinois Finance
     Development Authority or the Company with respect to the Project or the
     operation thereof, including, without limitation, federal, state or other
     ad valorem property, income or other taxes, other than ad valorem taxes
     presently levied upon privately owned property used for the same general
     purposes as the Project; or

          (ii)   if changes in the economic availability of raw materials,
     operating supplies, fuel or other energy sources or supplies, or facilities
     necessary for the operation of the Project or such technological or other
     changes shall have occurred which, in the Company's reasonable judgment,
     render the Project uneconomic for such purposes; or

          (iii)  any court or administrative body shall enter an order or decree
     preventing operations at the Project for six consecutive months; or

          (iv)   any court or administrative agency shall issue an order, decree
     or regulation the compliance with which would, in the opinion of the
     Company, render the continuation of the Project's operations economically
     unfeasible.

     (b) The bonds of Series KK are subject to optional redemption prior to
maturity by the Company on or after February 1, 2013, in whole at any time or in
part on any interest payment date, at the redemption price of 100% of the
principal amount thereof plus accrued interest, if any, to the redemption date.

                                       13
<Page>

     (c) All of the outstanding bonds of Series KK may be redeemed at any time
by the Company, by the payment of the principal amount thereof and accrued
interest thereon to the date of redemption, without the payment of any premium,
in the event of the acquisition by any federal, state or municipal authority of
any substantial portion (which shall be not less than one-third as determined by
book values) of the income-producing properties of the Company which are subject
to the lien of the Mortgage.

     (d) The bonds of Series KK are subject to mandatory redemption at any time,
in whole (or in part, as hereinafter provided), at 100% of the principal amount
thereof, plus accrued interest, if any, to the redemption date, in the event
that it is finally determined by the Internal Revenue Service or by a court of
competent jurisdiction that, as a result of the failure by the Company to
observe any covenant, agreement or representation in the Agreement, the interest
payable on the Revenue Bonds is includable for federal income tax purposes in
the gross income of any owner thereof, other than an owner who is a "substantial
user" of the Project or a "related person" of such substantial user, as provided
in Section 147(a) of the Code, and the applicable regulations thereunder. For
purposes of this paragraph (d), the "owner" of a Revenue Bond includes a
"Beneficial Owner" as defined in the Revenue Bond Indenture. Any such
determination will not be considered final for this purpose unless the Company
has been given written notice and, if it so desires, has been afforded the
opportunity to contest the same, either directly or in the name of any owner of
a Revenue Bond, and until the conclusion of any appellate review, if sought. The
bonds of Series KK shall be redeemed in whole after such determination unless
redemption of a portion of the Revenue Bonds outstanding would have the result
that interest payable on the Revenue Bonds remaining outstanding after such
redemption would not be includable for federal income tax purposes in the gross
income of any owner of the Revenue Bonds (other than an owner who is a
"substantial user" of the Project or a "related person" of such substantial user
within the meaning of Section 147(a) of the Code) and in such event the bonds of
Series KK shall be redeemed (in the principal amount of $5,000 or any integral
multiple thereof) in such amount as to accomplish that result. Any redemption
pursuant to this subparagraph (d) shall be on any date within one hundred and
eighty (180) days from the time of such final determination.

     (e) All of the outstanding bonds of Series KK shall be redeemed by the
Company not more than sixty (60) days after the Trustee receives written notice
from the Revenue Bond Trustee stating that the principal on the Revenue Bonds
has been declared to be immediately due and payable as a result of an event of
default under the Revenue Bond Indenture. The redemption price for any such
redemption shall be 100% of the principal amount of the bonds of Series KK to be
redeemed, plus interest thereon accrued to the date fixed for redemption.

     SECTION 6. If bonds of Series KK are to be redeemed as provided in Section
5

                                       14
<Page>

of this Article I, notice of redemption shall be mailed by or on behalf of the
Company, postage prepaid, at least thirty (30) days and not more than sixty (60)
days prior to such date of redemption, to the registered owners of all bonds of
Series KK to be so redeemed, at their respective addresses appearing upon the
registry book. Any notice which is mailed as herein provided shall be
conclusively presumed to have been properly and sufficiently given on the date
of such mailing, whether or not the holder receives the notice. In any case,
failure to give due notice by mail, or any defect in the notice, to the
registered owners of any bonds of Series KK designated for redemption as a whole
or in part, shall not affect the validity of the proceedings for the redemption
of any other bond of Series KK. In case of any redemption of bonds of Series KK
by the Trustee pursuant to the provisions of the Mortgage or any indenture
supplemental thereto, notice of redemption shall be given in a similar manner by
the Trustee.

     Except as provided above, the provisions of Article VI of the Mortgage
shall in all respects apply to any such redemption.

     SECTION 7. Bonds of Series KK shall bear the following legend: "This Bond
may not be sold, transferred, pledged or hypothecated except as required to
effect assignment to the Revenue Bond Trustee and to any successor trustee."

     SECTION 8. In this Supplemental Indenture, the following terms shall have
the meanings specified in this Section 9, unless the context otherwise requires:

          "Agreement" or "Loan Agreement" means the Loan Agreement executed by
     and between the Illinois Development Finance Authority and the Company
     dated as of February 1, 2003 with respect to the Revenue Bonds, as from
     time to time amended and supplemented.

          "Business Day" means any day which is not a Sunday or a legal holiday
     or a day (including Saturday) on which banking institutions in Chicago,
     Illinois, in New York, New York, and in the city where the Principal Office
     of the Revenue Bond Trustee is located are not required or authorized to
     remain closed and other than a day on which the New York Stock Exchange is
     not closed.

          "Code" means the Internal Revenue Code of 1986, as amended, and all
     regulations promulgated thereunder.

          "Project" means the land, structures, machinery, equipment, systems or
     processes, or any portion thereof, which are described in Exhibit A to the
     Agreement, as said Exhibit A may from time to time be amended.

          "Revenue Bonds" means the Gas Supply Refunding Revenue Bonds, Series
     2003A (The Peoples Gas Light and Coke Company Project), issued by the
     Illinois Development Finance Authority in the aggregate principal amount of
     $50,000,000.

                                       15
<Page>

          "Revenue Bond Indenture" means that certain Indenture of Trust
     executed by and between the Illinois Development Finance Authority and the
     Revenue Bond Trustee, dated as of February 1, 2003, and any amendments or
     supplements thereto, pursuant to which the Revenue Bonds may be issued.

          "Revenue Bond Trustee" means Bank One Trust Company, National
     Association, and any successor trustee appointed pursuant to Sections 1005
     or 1009 of the Revenue Bond Indenture at the time serving as successor
     trustee thereunder and shall include any co-trustee serving as such
     thereunder.

     SECTION 9. In any case where the date of maturity of interest on or
principal of the bonds of Series KK or the date fixed for redemption of any
bonds of Series KK shall be in the location of the principal office of the
Trustee, a Saturday, Sunday or a legal holiday or a day on which banking
institutions are authorized by law to close in the State of Illinois, then
payment of interest or principal (and premium, if any) need not be made on such
date but may be made on the next succeeding Business Day with the same force and
effect as if made on the date of maturity or the date fixed for redemption, and
no interest shall accrue for the period after such date.

     SECTION 10. The Company reserves the right, without any consent or other
action by holders of the bonds of Series KK or any subsequent series of bonds,
to amend the Mortgage by inserting the following language as Section 4 of
Article XVI immediately following current Section 3 of Article XVI of the
Mortgage:

     SECTION 4. Anything in Section 1 of this Article to the contrary
     notwithstanding, with the consent of the holders of not less than sixty per
     centum (60%) in aggregate principal amount of the bonds at the time
     outstanding or their attorneys-in-fact duly authorized, or, if the rights
     of the holders of one or more, but not all, series then outstanding are
     affected, the consent of the holders of not less than sixty per centum
     (60%) in aggregate principal amount of the bonds at the time outstanding of
     all affected series, taken together, and not any other series, the Company,
     when authorized by resolution of its Board of Directors, and the Trustee,
     from time to time and at any time, subject to the restrictions in this
     Mortgage contained, may enter into an indenture or indentures supplemental
     hereto for the purpose of adding any provisions to or changing in any
     manner or eliminating any of the provisions of this Indenture or of any
     supplemental indenture or modifying the rights and obligations of the
     Company and the rights of the holders of any of the bonds and coupons;
     provided, however, that no such supplemental indenture shall (1) extend the
     maturity of any of the bonds or reduce the rate or extend the time of
     payment of interest thereon, or reduce the amount of the principal thereof,
     or reduce any premium payable on the

                                       16
<Page>

     redemption thereof or change the coin or currency in which any bond or
     interest thereon is payable, without the consent of the holder of each bond
     so affected, or (2) permit the creation of any lien, not otherwise
     permitted, prior to or on a parity with the lien of the Mortgage, without
     the consent of the holders of all the bonds then outstanding, or (3) reduce
     the aforesaid percentage of the aggregate principal amount of bonds the
     holders of which are required to approve any such supplemental indenture,
     without the consent of the holders of all the bonds then outstanding. For
     the purposes of this Section 4, bonds shall be deemed to be affected by a
     supplemental indenture if such supplemental indenture adversely affects or
     diminishes the rights of holders thereof against the Company or against its
     property.

     Upon the written request of the Company, accompanied by resolution of its
     Board of Directors authorizing the execution of any such supplemental
     indenture, and upon the filing with the Trustee of evidence of the consent
     of bondholders as aforesaid (the instrument or instruments evidencing such
     consent to be dated within one year of such request), the Trustee shall
     join with the Company in the execution of such supplemental indenture
     unless such supplemental indenture affects the Trustee's own rights, duties
     or immunities under this Mortgage or otherwise, in which case the Trustee
     may in its discretion but shall not be obligated to enter into such
     supplemental indenture. The Trustee shall be entitled to receive and,
     subject to Section 7 of Article XV hereof, may rely upon, an opinion of
     counsel as conclusive evidence that any such supplemental indenture is
     authorized or permitted by the provisions of this Section 4.

     It shall not be necessary for the consent of the bondholders under this
     Section 4 to approve the particular form of any proposed supplemental
     indenture, but it shall be sufficient if such consent shall approve the
     substance thereof.

     The Company and the Trustee, if they so elect, and either before or after
     such 60% or greater consent has been obtained, may require the holder of
     any bond consenting to the execution of any such supplemental indenture to
     submit his bond to the Trustee or to such bank, banker or trust company as
     may be designated by the Trustee for the purpose, for the notation thereon
     of the fact that the holder of such bond has consented to the execution of
     such supplemental indenture, and in such case such notation, in form
     satisfactory to the Trustee, shall be made upon all bonds so submitted, and
     such bonds bearing such notation shall forthwith be returned to the persons
     entitled thereto. All subsequent holders of bonds bearing such notation
     shall be deemed to have consented to the execution of such supplemental
     indenture, and consent, once given or deemed to be given, may not be
     withdrawn.

                                       17
<Page>

     Prior to the execution by the Company and the Trustee of any supplemental
     indenture pursuant to the provisions of this Section 4, the Company shall
     publish a notice, setting forth in general terms the substance of such
     supplemental indenture, at least once in one daily newspaper of general
     circulation in each city in which the principal of any of the bonds shall
     be payable, or, if all bonds outstanding of any series shall be registered
     bonds without coupons or coupon bonds registered as to principal, such
     notice with respect to such series shall be mailed first class, postage
     prepaid, and registered if the Company so elects, to each registered holder
     of bonds of such series at the last address of such holder appearing on the
     registry books, such publication or mailing, as the case may be, to be made
     not less than thirty (30) days prior to such execution. Any failure of the
     Company to give such notice, or any defect therein, shall not, however, in
     any way impair or affect the validity of any such supplemental indenture.

                                   ARTICLE II

                            COVENANTS OF THE COMPANY

     SECTION 1. The Company covenants and agrees, so long as any of the bonds of
Series KK are outstanding or until provision shall have been made for the
redemption or payment thereof by the deposit with the Trustee of money necessary
to effect such redemption or payment, as follows:

          (a)    The Company, during or at the close of the calendar year 2003,
     and during or at the close of each calendar year thereafter, shall charge
     against the income for such calendar year and place to the credit of a
     "depreciation reserve account" to be kept on its books, the greater of the
     following two amounts: (i) the amount of $1,550,000, or (ii) an amount
     equal to 2 1/2% of the sum of

                 (i)  the aggregate principal amount of all bonds which, at the
          time such credit is placed to said "depreciation reserve account",
          shall be outstanding and shall have been outstanding under the
          Mortgage as supplemented for a period of not less than six (6) months,
          or which at such time shall have been outstanding under the Mortgage
          supplemented for less than six (6) months, if such bonds shall have
          been issued, or the proceeds thereof shall have been used, directly or
          indirectly, for or on account of the pledge, acquisition, exchange,
          cancellation, payment, refundment, redemption or discharge at, before
          or after maturity of the bonds of any series theretofore issued under
          the Mortgage or of any "underlying bonds" or "specified obligations"
          as defined in Section 4 of Article III of the Mortgage; and

                 (ii) the aggregate principal of all indebtedness of the Company
          secured by a mortgage lien upon the properties or assets of the
          Company, which is a lien superior to the lien of the Mortgage, except
          (A) any such

                                       18
<Page>

          mortgage indebtedness the evidences of which shall then be pledged
          with the Trustee under the provisions of the Mortgage or pledged with
          the Trustee under any mortgage constituting a lien superior to the
          lien of the Mortgage on any part of the properties or assets of the
          Company, and (B) any such mortgage indebtedness for the payment or
          redemption of which the necessary moneys shall have been deposited
          with the Trustee under the Mortgage securing the same; provided,
          however, that (1) the amount required by this subparagraph (a) to be
          placed to the credit of such "depreciation reserve account" in or for
          any calendar year shall be deemed to include and not to be in addition
          to amounts which, by the provisions of the Mortgage, the Company is
          required to add to any depreciation reserve account for such year, (2)
          nothing in this subparagraph (a) shall prevent the Company from
          crediting to such "depreciation reserve account", during or at the
          close of any calendar year, an amount greater than the amount required
          by this subparagraph (a) for such year, and (3) the Company may, from
          time to time, during each such calendar year, charge against such
          "depreciation reserve account" the cost of depreciable property
          retired by it during such year, including the cost, if any, of
          dismantling such retired property, less any salvage credits applicable
          thereto.

            (b)  The Company after it shall have issued bonds of Series KK in
     the aggregate principal amount of $50,000,000, shall not request the
     Trustee

                    (i)  to authenticate bonds of any series under the Mortgage

                              (A)  pursuant  to Section 2 of Article  III of the
                 Mortgage for or on account of the acquisition and cancellation,
                 or of the payment, cancellation, redemption or other discharge
                 at, before or after maturity, affected prior to January 1,
                 1951, of any bonds of any series theretofore issued under the
                 Mortgage, or

                              (B)  pursuant  to Section 4 of Article III of the
                 Mortgage, for or on account of the pledge, acquisition,
                 exchange, cancellation, payment, refundment, redemption or
                 discharge effected prior to January 1, 1951, of "underlying
                 bonds" or "specified obligations" mentioned in said Section 4,
                 or

                              (C)  pursuant  to Section 5 of Article III of the
                 Mortgage, for or in respect of expenditures made prior to
                 January 1, 1951, for or on account of "permanent property", or

                    (ii) to pay to the Company any cash pursuant to Section 6 of
          said Article III for or on account of any transactions mentioned in
          clause (A) or clause (B) of subdivision (i) of this subparagraph (b)
          or for or in respect of any expenditures mentioned in clause (C) of
          subdivision (i) of this subparagraph (b).

                                       19
<Page>

     Neither shall the Company request the Trustee to authenticate bonds of any
     series under the provisions of Section 4 of Article III of the Mortgage or
     to pay the Company any moneys under Section 6 of said Article III or under
     Article IX of the Mortgage for or on account of the payment, discharge and
     cancellation effected on or after January 1, 1944, at, before or after
     maturity of any of the Refunding Mortgage Five Per Cent Gold Bonds of the
     Company, dated September 1, 1897, due September 1, 1947.

            (c)  The Company shall not request the Trustee to authenticate bonds
     of any series under the Mortgage or to pay to the Company any cash
     deposited with or received by the Trustee under the Mortgage (except cash
     deposited with or received by the Trustee as and for a sinking fund for any
     series of bonds which have been or may hereafter be issued under the
     Mortgage), unless the Company as a part of such request, and in addition to
     all other documents required by the Mortgage to be delivered to the Trustee
     in connection with such request, shall deliver to the Trustee a certificate
     or certificates, signed by the President or the Executive Vice President or
     the Chief Financial Officer or a Vice President and by the Treasurer or an
     Assistant Treasurer of the Company

                 (i)  showing, in case such request is for the authentication
          of bonds pursuant to Section 5 of Article III of the Mortgage or for
          the payment of cash pursuant to Section 6 of said Article III for or
          in respect of expenditures made by the Company on or after January 1,
          1951, for or on account of "permanent property":

                              (A) the total amount of expenditures  (reduced to
               the extent required, if any, by the provisions of clause (G) of
               this subdivision (i)) made on or after January 1, 1951, for or on
               account of "permanent property";

                              (B) the  original  cost of all  properties,
               subject to the lien of the Mortgage at any time on or after
               January 1, 1951, replaced or retired on or after January 1, 1951,
               less, if any such property shall have been released from the lien
               of the Mortgage pursuant to any applicable provision of the
               Mortgage and to obtain such release cash shall have been
               deposited with the Trustee, the amount of such cash;

                              (C) an  amount  equal  to the  sum of
               (1) 133-1/3% of the aggregate principal amount of bonds which
               have been authenticated after January 1, 1951, pursuant to
               Section 5 of Article III of the Mortgage for or on account of
               such expenditures made on or after January 1, 1951, plus (2)
               133-1/3% of the aggregate amount of deposited cash withdrawn
               after January 1, 1951, pursuant to the provisions of Section 6 of
               Article III of the Mortgage for or in respect of such
               expenditures made on or after January 1, 1951, plus (3) 133-

                                       20
<Page>

               1/3% of the aggregate amount of excess of the nature described in
               subdivision (2) of Section 4 of Article III of the Mortgage
               eliminated or compensated, as in said subdivision (2) provided,
               for or in respect of expenditures of the Company for or on
               account of "permanent property" during said period commencing
               January 1, 1951;

                              (D)  an  amount  equal  to  100%  of the aggregate
               amount of moneys withdrawn by the Company pursuant to the
               provisions of Article IX of the Mortgage on or after January 1,
               1951, for or in respect of expenditures made for or on account of
               "permanent property";

                              (E) an  amount  equal  to the  excess,  if  any,
               of the amount shown pursuant to clause (A) above over the sum of
               the amounts shown pursuant to clauses (B), (C) and (D) above;

                              (F) that, for a period of twelve (12)  consecutive
               calendar months (to be selected by the Company) ending within
               ninety (90) days next preceding such request, the "net earnings
               of the Company" shall have been at least twice the amount of the
               annual interest requirement of all "mortgage and prior lien debt
               of the Company";

                              (G) that the amount of the expenditure, if any,
               included in the expenditures set forth in clause (A) above
               in respect of any particular "permanent property", which at the
               time of its acquisition was subject to the lien of any mortgage
               existing or placed thereon at the time of its acquisition, does
               not exceed an amount equal to the excess, if any, of the value
               (determined as provided in the first paragraph of Section 8 of
               Article III of the Mortgage) of such particular "permanent
               property" at the time of acquisition of such property over
               133-1/3% of the principal amount of all indebtedness secured by
               all such mortgages existing or placed on such particular property
               at the time of the acquisition thereof, and that the amount of
               the expenditure, if any, included in the expenditures set forth
               in clause (A) above in respect of any particular "permanent
               property", which at the time of its acquisition was not subject
               to any such lien, does not exceed an amount equal to the value
               (determined as provided in the first paragraph of Section 8 of
               Article III of the Mortgage) of such particular "permanent
               property" at the time of acquisition of such property;

                 (ii)  showing, in case such request is for the authentication
          of bonds pursuant to Section 4 of Article III of the Mortgage or for
          the payment of cash pursuant to Section 6 of said Article III for or
          on account of the pledge, acquisition, exchange, cancellation,
          payment, refundment,

                                       21
<Page>

          redemption or discharge effected on or after January 1, 1951, at,
          before or after maturity of any "specified obligations" mentioned in
          said Section 4, that at the time such "specified obligations" became
          "specified obligations" or at some later date the Company, pursuant to
          the provisions of Section 5 of Article III of the Mortgage, as limited
          by the provisions of this Section I, shall have obtained, or shall
          have had the right to obtain, the authentication and delivery of bonds
          in any principal amount for or in respect of expenditures made on or
          after January 1, 1951, for or on account of "permanent property";

                 (iii) showing, in case such request shall be for the payment of
          moneys pursuant to Article IX of the Mortgage for or in respect of
          expenditures made for or on account of "permanent property", that none
          of such expenditures were made (1) prior to January 1, 1951, or (2)
          for or on account of "permanent property" acquired more than six
          months prior to the date when the Trustee received the moneys so to be
          paid (or in case of moneys representing the proceeds of obligations,
          referred to in said Article IX, the date when the Trustee received
          such obligations); and

                 (iv)  showing, in case such request is for the application of
          any moneys pursuant to Article IX of the Mortgage to the payment,
          redemption or purchase of any "specified obligations", that such
          "specified obligations", if pledged under the Mortgage, would permit
          the Company to obtain the authentication of bonds in a principal
          amount equal to the principal amount of such "specified obligations"
          pursuant to the provisions of Section 4 of Article III of the Mortgage
          as limited by the provisions of this Section 1.

          (d) In connection with any request for the authentication of bonds
     pursuant to Section 5 of Article III of the Mortgage or the payment of cash
     pursuant to Section 6 of said Article III of Mortgage, for or in respect of
     expenditures made by the Company on or after January 1, 1951, the Company
     shall not obtain the authentication of bonds of any series under the
     Mortgage or the payment of any cash in excess of 75% of the amount shown in
     the certificate delivered as a part of such request pursuant to clause (E)
     of subdivision (i) of subparagraph (c) of this Section 1; and the Company
     shall not obtain the authentication of any bonds or the payment of any cash
     deposited with or received by the Trustee under the Mortgage otherwise than
     in accordance with the provisions of the Mortgage as supplemented.

          (e) Wherever used in this Supplemental Indenture

                 (i) "mortgage and prior lien debt of the Company", as of the
          date of any request to the Trustee for the authentication of bonds or
          the payment of cash, shall mean:

                                       22
<Page>

                              (A) all the bonds then outstanding under the
               Mortgage, less the amount of any of such bonds which shall then
               be held by or be delivered to the Trustee for cancellation under
               any of the provisions of the Mortgage, and less the amount of any
               such bonds for the payment or redemption of which the necessary
               moneys shall have been deposited under the Mortgage with the
               Trustee to effect such payment or redemption;

                              (B) the bonds then requested to be authenticated
               under the Mortgage; and

                              (C) all mortgage indebtedness secured by a lien
               superior to the lien of the Mortgage on any part of the
               properties and assets of the Company, except any such mortgage
               indebtedness the evidences of which shall then be pledged with
               the Trustee under the provisions of the Mortgage or pledged with
               the Trustee under any mortgage constituting a lien superior to
               the lien of the Mortgage on any part of the properties and assets
               of the Company, and except any such mortgage indebtedness for the
               payment or redemption of which the necessary moneys shall have
               been deposited with the trustee under the mortgage securing the
               same to effect such payment or redemption;

                 (ii) "net earnings of the Company" for any twelve (12) months'
          period shall mean the amount remaining after deducting from the sum of

                              (A) the gross operating revenues of the Company
               for such period derived from its property subject to the lien of
               the Mortgage, including but not limited to revenues derived from
               electrical energy, gas or steam purchased by the Company and
               resold by it, and the net income derived by the Company from its
               merchandising and jobbing operations; and

                              (B) other income of the Company for such period
               derived from interest on bank balances and from current working
               capital invested in unpledged obligations of the United States of
               America or of any state or of any municipality or subdivision
               thereof, and other currently earned income of the Company derived
               from the ownership of securities, in the treasury of the Company
               and unpledged, of operating electric, gas or steam companies
               (including natural or mixed gas production, storage,
               transportation or distribution companies) or from unpledged
               advances to such companies any of the securities of which are so
               owned, the sum of the following:

                              (C) operating expenses of the Company for such
               period, including maintenance and repairs, rentals, taxes (except
               taxes based upon net income), insurance and the cost of
               electrical energy, gas or

                                       23
<Page>

               steam purchased for resale, but excepting expenses in connection
               with operations, the net income only of which is included in
               clause (A) of subdivision (ii) of this subparagraph (e), and
               excepting all reserves or charges for amortization of debt
               discount and expense; and

                              (D) an amount, if such period shall end with the
               close of a calendar year, equal to the amount which the Company
               is required by subparagraph (a) of this Section 1 to place,
               during or at the close of such calendar year, to the credit of
               the "depreciation reserve account", mentioned in said
               subparagraph (a) (all determined without deduction for any charge
               made to the "depreciation reserve account" permitted by clause
               (3) of the proviso of subparagraph (a) of this Section 1), or, if
               such period shall include parts of two (2) calendar years, then
               an amount which shall be determined by (1) prorating, on a
               monthly basis over the portion of the earlier year thus included,
               the amount which the Company shall have been so required to
               credit to the "depreciation reserve account" during or at the
               close of such earlier year, and (2) prorating, on a monthly basis
               over the portion of the later of said two (2) years thus
               included, the amount which the Company would be required to
               credit to such "depreciation reserve account" if such credit were
               placed to such account at the close of such period;

          provided, however, that the amount of other income of the Company,
          referred to in clause (B) of subdivision (ii) of this subparagraph
          (e), shall not exceed 10% of said net earnings; and income in the form
          of dividends received by the Company upon stock of any class owned by
          it shall be considered as currently earned under the provisions of
          said clause (B) to the extent that during such period the earnings of
          the paying company shall be sufficient for the payment of dividends
          upon all stock of such class during such period; and income in the
          form of interest received by the Company upon evidences of
          indebtedness of any class owned by it shall be considered as currently
          earned under the provisions of said clause (B) to the extent that
          during such period the earnings of the paying company shall be
          available for the payment of the interest accruing during such period
          upon all indebtedness of such class, after deducting from such
          earnings all interest charges accruing during such period upon
          obligations secured by prior liens; and, in case any property owned by
          the Company at the date of the request to the Trustee for the
          authentication of bonds or payment or withdrawal of cash shall not
          have been owned by it during any part of any such period, or shall
          have been owned by it during a part only of such period, then and in
          every such case the net earnings (or net losses) of such property
          (ascertained in like manner as above provided) during said period, or
          during such part thereof as shall have preceded the acquisition of
          such property by the Company, shall be considered and treated as net
          earnings (or net losses) of the Company for such period, and shall be
          included in (or, if a net loss, deducted in determining) such net
          earnings of

                                       24
<Page>

          the Company;

                    (iii) "permanent property" shall mean any and all plants,
               equipment, additions, improvements, betterments, facilities, or
               other property of any kind (and includes "extensions" and
               "purchased property" as those terms are used in the Mortgage)
               acquired through construction, purchase, consolidation, exchange
               or otherwise, as and for a part of the permanent or fixed
               investment for the business of the Company and used or useful in
               connection with the generation and conversion of electrical
               energy or in the manufacture of gas or steam or in the
               distribution or transmission of electrical energy or gas or steam
               in the territory in which the Company is now operating its
               present properties, or in territory contiguous thereto, or in
               territory capable of economic interconnection therewith, but
               "permanent property" shall not include cash, accounts or bills
               receivable, securities, supplies, fuel or other assets ordinarily
               classed as quick assets, or leasehold estates;

                    (iv) "original cost" of property shall mean the original
               cost of such property to the Company if ascertainable from its
               records or, if such original cost is not ascertainable, the value
               of such property at the time of its acquisition, such value to be
               determined by an engineer or firm of engineers to be selected by
               the Company and to be acceptable to the Trustee, and the Trustee
               under such circumstances shall be furnished with a certificate of
               such value signed by such engineer or firm of engineers.

               (f) In connection with any request to the Trustee for the
     authentication of bonds pursuant to the provisions of Section 5 of Article
     III of the Mortgage or the payment of cash pursuant to the provisions of
     Section 6 of said Article III or the provisions of Article IX of the
     Mortgage or the elimination or compensation of any excess of the nature
     described in subdivision (2) of Section 4 of said Article III, for or on
     account of expenditures for "permanent property", the Company shall furnish
     to the Trustee, in addition to the certificates and other documents
     required to be delivered by the provisions of the Mortgage and the
     provisions of other subparagraphs of this Section 1, the following:

                    (i) An opinion of counsel (who may be counsel for the
               Company), selected by the Company and satisfactory to the
               Trustee, stating that the Company has acquired good title to the
               property for or on account of the expenditures for which
               additional bonds are requested to be authenticated and that such
               property is subject to the Mortgage as a direct lien thereon,
               subject only to the lien of any mortgages or easements existing
               or placed on any of such property at the time of its acquisition,
               liens for taxes and assessments not due or, if due, in the course
               of contest, judgments in the course of appeal or otherwise in
               contest and secured by sufficient bond, liens arising out of
               proceedings in court in the course of contest and undetermined
               liens charges (if any) incidental to current construction; and

                                       25
<Page>

                    (ii) A certificate signed by the President or the Executive
               Vice President or the Chief Financial Officer or a Vice President
               and also by the Treasurer or an Assistant Treasurer of the
               Company certifying that the property for or on account of the
               expenditures for which bonds are requested to be authenticated or
               cash is requested to be paid is "permanent property".

               (g) The Company shall not hereafter issue any bonds under any
     "underlying mortgage" as defined in Section 4 of Article III of the
     Mortgage, or under any mortgage which could become such an "underlying
     mortgage" upon compliance with clause (b) of the proviso of subdivision (2)
     of said Section 4.

               (h) The Company shall not request the Trustee to authenticate
     any bonds under the provisions of Section 2 or Section 3 or Section 4 of
     Article III of the Mortgage and shall not apply for the payment of cash
     under Section 6 of said Article or under Article IX of the Mortgage (i) for
     or on account of bonds of Series J deposited by the Company with the
     Trustee in lieu of cash under the provisions of the sinking fund provided
     for in the supplemental indenture, dated as of May 1, 1961, or for or on
     account of bonds of Series J redeemed through the operation of said sinking
     fund, or (ii) for or on account of bonds of Series K redeemed through the
     operation of the sinking fund provided for in the supplemental indenture
     dated as of July 15, 1966, or (iii) for or on account of bonds of Series L
     redeemed through the operation of the sinking fund provided for in the
     supplemental indenture dated as of August 15, 1967, or (iv) for or on
     account of bonds of Series M redeemed through the operation of the sinking
     fund provided for in the supplemental indenture dated as of September 15,
     1970, or (v) for or on account of bonds of Series N redeemed through the
     operation of the sinking fund provided for in the supplemental indenture
     dated as of April 1, 1972, or (vi) for or on account of bonds of Series 0
     redeemed through the operation of the sinking fund provided for in the
     supplemental indenture dated as of July 15, 1973, or (vii) for or on
     account of bonds of Series T redeemed through the operation of the sinking
     fund provided for in the supplemental indenture dated as of August 15,
     1980, or (viii) on account of any cancelled or uncancelled underlying bonds
     (or any uncancelled underlying bonds deposited as collateral under Section
     4 of Article III of the Mortgage) which shall have been deposited under the
     provisions of the supplemental indenture, dated as of August 1, 1941, in
     lieu of cash.

               (i) In the event of the acquisition at any time by any federal,
     state or municipal authority of all or substantially all of the
     income-producing properties of the Company which are subject to the lien of
     the Mortgage, the Company shall be deemed to have elected to redeem and to
     have requested the Trustee to redeem all the bonds of all series at the
     respective applicable redemption price or prices (together with accrued
     interest to the date of redemption), without the payment of any premium, on
     a date determined by the Trustee in its discretion to be

                                       26
<Page>

     the earliest practicable redemption date after receipt by the Trustee of
     all cash which the Trustee is entitled to receive in respect of such
     acquisition by such federal, state or municipal authority. If the cash so
     received by the Trustee and all other cash then held by the Trustee as
     such, except funds held in trust for the benefit of the holders of
     particular bonds and coupons, is not sufficient to effect the redemption of
     all the bonds of all series as aforesaid and to pay all amounts owing to
     the Trustee under the Mortgage as supplemented (including fees and expenses
     to be incurred by the Trustee in connection with such redemption), the
     Company covenants and agrees that, within five (5) days after receipt by
     the Trustee of all cash which the Trustee is entitled to receive as
     aforesaid in respect of such acquisition, the Company will deposit with the
     Trustee for that purpose cash in an amount sufficient to make up such
     deficiency.

     Upon receipt by the Trustee of moneys sufficient for said purposes, notice
     of such redemption shall be given by the Trustee for and on behalf and in
     the name of the Company. To the extent that such cash received, held and
     deposited as aforesaid shall be required for the purpose of redeeming bonds
     pursuant to this subparagraph (i), the Company shall be deemed to have
     directed the Trustee to apply the same for the purpose, and the balance, if
     any, after payment of all said amounts owing to the Trustee, shall be paid
     to or upon the order of the Company.

               (j) The Company shall promptly classify as "property replaced or
     retired", for the purposes of clause (B) of subdivision (i) of subparagraph
     (c) of this Section 1 during any period all property which has been
     replaced or has permanently ceased to be used or useful in the business of
     the Company, but the Company shall not, in making such classification, be
     bound by determinations, rulings or orders made by regulatory authorities
     for rate-making or other purposes.

               (k) The Company shall not consolidate with or merge into any
     other corporation or transfer or lease all or substantially all the
     mortgaged property as an entirety to any other corporation, unless the
     corporation resulting from such consolidation or the corporation into which
     the Company shall have been merged or the corporation to which such
     transfer or lease shall have been made shall, by an instrument executed and
     delivered to the Trustee, assume the due and punctual payment of the
     principal of and premium, if any, and interest on all the bonds of all
     series according to their tenor at the time outstanding under the Mortgage
     and the due and punctual performance and observance of all the covenants
     and conditions of the Mortgage and all indentures supplemental thereto to
     be performed or observed by the Company.

     SECTION 2. The Company covenants and agrees that any and all property
hereafter acquired by the Company and any and all improvements, extensions,
betterments or additions to property of the Company, which by the Original
Mortgage or any indenture supplemental thereto are to become subject to the
Mortgage, immediately upon the acquisition thereof by the Company or upon such
improvements, extension,

                                       27
<Page>

betterments, or addition being made, as the case may be, and without any further
conveyance, mortgage, assignment or act on the part of the Company or the
Trustee, or either of them shall become and be subject to the lien of the
Mortgage fully and completely as though owned by the Company at the date of the
execution of the Original Mortgage and at the date of the Indenture dated the
first day of March, 1928, mentioned in the second paragraph of the recitals of
this Supplemental Indenture and at the dates of the supplemental indentures
dated May 20, 1936, May 10, 1950, as of June 1, 1951, as of August 15, 1967, as
of September 15, 1970, as of March 1, 1985, as of April 1, 1993, as of December
1, 1993, as of December 1, 1993, as of June 1, 1995, as of March 1, 2000, as of
March 1, 2000, as of March 1, 2000 and as of March 1, 2000 respectively,
mentioned in the fourth paragraph of the recitals of this Supplemental
Indenture, and at the date of this Supplemental Indenture, and specifically
described in the granting clauses of the Original Mortgage or said Indenture or
said supplemental indentures, but the provisions of this Section 2 shall not
limit the generality of the provisions of Sections 12 and 13 of Article IV of
the Original Mortgage.

     SECTION 3. The Company covenants and agrees that in the furtherance of, but
without limiting the generality of, the provisions of Sections 12 and 13 of
Article IV of the Mortgage or of Section 2 of this Article II, the Company will
furnish to the Trustee on November 1, 1944, and thereafter within sixty (60)
days after and as often as the Company shall have acquired, subsequent to
September 3, 1944, any additional land or lands or interest or interests in
land, or any new plant or plants, not included in any certificate theretofore
furnished pursuant to this Section 3, the aggregate cost of which shall equal or
exceed $500,000, and at such other times as thirty-six (36) months shall have
elapsed since the date of furnishing the last preceding certificate to the
Trustee pursuant to this Section 3, the following:

          (a) a certificate, signed by the President or the Executive Vice
     President or the Chief Financial Officer or a Vice President and by the
     Treasurer or an Assistant Treasurer of the Company and dated as of a date
     not more than sixty (60) days preceding the date as of which such
     certificate is required to be filed pursuant to this Section 3, briefly
     describing any additional land or interest in land and any new plant which
     the Company may have acquired since the date of the most recent Certificate
     furnished to the Trustee pursuant to this Section, or, in the case of the
     first such certificate, since the date of the execution and delivery of the
     Indenture dated the first day of March, 1928 mentioned in the second
     paragraph of the recitals of this Supplemental Indenture, which is required
     by the provisions of the Mortgage and this Supplemental Indenture to be
     subjected to the lien of the Mortgage;

          (b) the mortgages, deeds, covenants, assignments, transfers and
     instruments of further assurance, if any, specified in the opinion of
     counsel referred to in the following subparagraph (c); and

          (c) an opinion of counsel, who may be counsel for the Company,
     specifying the mortgages, deeds, covenants, assignments, transfers and
     instruments of

                                       28
<Page>

     further assurance which will be sufficient to subject to the direct lien of
     the Mortgage (so far as permitted by law) all the Company's right, title
     and interest in and to the land and interest in land and any plant
     described in said certificate, or stating that no such mortgage, deed,
     conveyance, assignment, transfer or instrument of further assurance is
     necessary for such purpose, and that, upon the recordation or filing or
     registering, in the manner stated in such opinion, of the instruments so
     specified, if any, and upon the recordation and filing and registering of
     the Mortgage or any supplemental indenture in the manner stated in such
     opinion, or without any such recordation or filing or registering if such
     opinion shall so state, the Mortgage will (so far as permitted by law)
     constitute a valid lien upon all the Company's right, title and interest in
     and to such land, interest in land or plant as against all creditors and
     subsequent purchasers, subject only to the lien of any mortgages or
     easements existing or placed on such property at the time of its
     acquisition by the Company, liens for taxes and assessments not due, or, if
     due, in the course of appeal or otherwise in contest, liens arising out of
     proceedings in court in the course of contest and undetermined liens and
     charges (if any) incidental to current construction.

     For the purposes of this Section 3, any certificate heretofore or hereafter
delivered to the Trustee pursuant to Section 3 of Article III of Division B of
the supplemental indenture dated as of June 1, 1951, or pursuant to Section 3 of
Article II of the Supplemental Indenture dated as of July 1, 1954, or pursuant
to Section 3 of Article III of the supplemental indenture dated as of May 1,
1961, or pursuant to Section 3 of Article III of the supplemental indenture
dated as of July 15, 1966, or pursuant to Section 3 of Article III of the
supplemental indenture dated as of August 15, 1967, or pursuant to Section 3 of
Article III of the supplemental indenture dated as of September 15, 1970, or
pursuant to Section 3 of Article III of the supplemental indenture dated as of
April 1, 1972, or pursuant to Section 3 of Article III of the supplemental
indenture dated as of July 15, 1973, or pursuant to Section 3 of Article II of
the Supplemental Indenture dated as of October 1, 1973, or pursuant to Section 3
of Article II of the Supplemental Indenture dated as of October 1, 1974, or
pursuant to Section 3 of Article II of the Supplemental Indenture dated as of
December 1, 1974, or pursuant to Section 3 of Article II of the Supplemental
Indenture dated as of April 1, 1975, or pursuant to Section 3 of Article III of
the Supplemental Indenture dated as of August 15, 1980, or pursuant to Section 3
of Article II of the supplemental indenture dated as of June 1, 1984, or
pursuant to Section 3 of Article II of the supplemental indenture dated as of
June 1, 1984, or pursuant to Section 3 of Article II of the supplemental
indenture dated as of October 1, 1984, or pursuant to Section 3 of Article II of
the supplemental indenture dated as of March 1, 1985, or pursuant to Section 3
of Article II of the supplemental indenture dated as of March 1, 1985, or
pursuant to Section 3 of Article II of the supplemental indenture dated as of
March 1, 1985, or pursuant to Section 3 of Article II of the supplemental
indenture dated as of March 1, 1985, or pursuant to Section 3 of Article II of
the supplemental indenture dated as of May 1, 1990, or pursuant to Section 3 of
Article II of the supplemental indenture dated as of April 1, 1993, or pursuant
to Section 3 of Article II of the supplemental indenture dated as of December 1,

                                       29
<Page>

1993, or pursuant to Section 3 of Article II of the supplemental indenture dated
as of December 1, 1993, or pursuant to Section 3 of Article II of the
supplemental indenture dated as of June 1, 1995, or pursuant to Section 3 of
Article II of the supplemental indenture dated as of March 1, 2000, or pursuant
to Section 3 of Article II of the supplemental indenture dated as of March 1,
2000, or pursuant to Section 3 of Article II of the supplemental indenture dated
as of March 1, 2000, or pursuant to Section 3 of Article II of the supplemental
indenture dated as of March 1, 2000 shall be deemed to have been delivered in
compliance with this Section 3.

     SECTION 4. The Company covenants and agrees that, upon cancellation and
discharge of any "prior lien", the Company shall cause all cash or obligations
then held by the trustee or other holder of such prior lien, which were received
by such trustee or other holder by reason of the release of, or which represent
the proceeds of the taking by eminent domain or any disposition of, or the
proceeds of insurance on, any of the properties at any time subject to the lien
of the Mortgage (including all proceeds of or substitutions for any thereof), to
be paid to or deposited and pledged with the Trustee, subject to any lien or
charge prior to the lien of the Mortgage, such cash to be held and paid over or
applied by the Trustee, and such obligations to be held and disposed of, as
provided in Article IX of the Mortgage; provided, however, that in lieu of
taking or delivering to the Trustee all or any part of such cash or obligations,
the Company may deliver to the Trustee a certificate of the trustee or such
other holder of such prior lien, stating that a specified amount thereof has
been deposited with such trustee or other holder pursuant to the requirements of
such other prior lien, in which case there shall also be delivered to the
Trustee an opinion of counsel, who may be counsel for the Company, stating that
such deposit is required by such other prior lien. The term "prior lien" as used
in this Section 4 shall mean and include any "underlying mortgage" and shall
also mean and include any other lien (except liens for taxes and assessments not
due, or, if due, in the course of appeal or otherwise in contest, liens arising
out of proceedings in court in course of contest and undetermined liens and
charges, if any, incidental to current construction) prior to the lien of the
Mortgage upon property acquired by the Company after the execution and delivery
of the Indenture, dated the first day of March, 1928, referred to in the second
paragraph of the recitals of this Supplemental Indenture, existing on said
property or placed thereon to secure unpaid portions of the purchase price, at
the time of such acquisition.


                                   ARTICLE III

                                  MISCELLANEOUS

     SECTION 1. The Trustee hereby accepts the trusts hereunder and agrees to
perform the same upon the terms and subject to the applicable provisions of the
Mortgage and the indentures supplemental thereto now in effect.

                                       30
<Page>

     SECTION 2. This Supplemental Indenture is executed by the parties hereto
pursuant to the provisions of Article XVI of the Mortgage, and so long as any of
the bonds of Series KK are or shall be outstanding the terms and conditions of
this Supplemental Indenture shall be deemed to be a part of the terms and
conditions of the Mortgage for any and all purposes. The provisions of this
Supplemental Indenture shall be inapplicable and shall terminate and become void
and of no effect upon the payment or redemption of all of the bonds of Series KK
in accordance with the provisions of the Mortgage and of the bonds of Series KK.

     SECTION 3. All covenants, conditions and provisions contained in this
Supplemental Indenture by or on behalf of the Company shall bind its successors
and assigns, whether so expressed or not, legally or equitably under or by
reason of this Supplemental Indenture.

     SECTION 4. Although this Supplemental Indenture is dated as of February 1,
2003, it shall be effective only from the actual time of its execution and
delivery by the Company and the Trustee on the date indicated by their
respective acknowledgments hereto annexed.

     This Supplemental Indenture may be simultaneously executed in any number of
counterparts and all such counterparts executed and delivered, each as an
original, shall constitute but one and the same instrument entered into by the
parties hereto pursuant to the provisions of Article XVI of the Mortgage.

                                       31
<Page>

  IN WITNESS WHEREOF, THE PEOPLES GAS LIGHT AND COKE COMPANY has caused this
instrument to be executed in its corporate name by its Chairman, President, the
Executive Vice President, the Chief Financial Officer or a Vice President, and
its corporate seal to be hereunto affixed and attested by its Secretary or an
Assistant Secretary, and U.S. Bank National Association, as Trustee under the
Mortgage, has caused this instrument to be executed in its corporate name by one
of its Vice Presidents and its corporate seal to be hereto affixed and attested
by one of its Trust Officers, all as of the day and year first above written.

                      THE PEOPLES GAS LIGHT AND COKE COMPANY


                          By  /s/ Thomas A. Nardi
                             --------------------------
                              Thomas A. Nardi
                              Senior Vice President, Chief Financial Officer and
                              Treasurer

ATTEST:

/s/ J.G. Nassos
---------------
     J.G. Nassos
     Assistant Secretary

                      U.S. BANK NATIONAL ASSOCIATION

                          By  /s/ Richard H. Prokosch_
                             --------------------------
                              Richard H. Prokosch
                              Vice President

ATTEST:

/s/ Frank P. Leslie, Iii
------------------------
     Frank P. Leslie, III
     Vice President

                                       32
<Page>

STATE OF ILLINOIS   )
                    )  ss.
COUNTY OF COOK      )


   I, Lorena Patino, a Notary Public in and for said County and State aforesaid,
DO HEREBY CERTIFY that THOMAS A. NARDI, the Senior Vice President, Chief
Financial Officer and Treasurer of The Peoples Gas Light and Coke Company, an
Illinois corporation, and JOHN G. NASSOS, Assistant Secretary of said
corporation, who are both personally known to me to be the same persons whose
names are subscribed to the foregoing instrument as such Senior Vice President,
Chief Financial Officer and Treasurer and Assistant Secretary, respectively, and
who are both personally known to me to be the Senior Vice President, Chief
Financial Officer and Treasurer and Assistant Secretary, respectively, of said
corporation, appeared before me this day in person and severally acknowledged
that they signed, sealed and delivered said instrument as their free and
voluntary act as such Senior Vice President, Chief Financial Officer and
Treasurer and Assistant Secretary, respectively, of said corporation, and as the
free and voluntary act of said corporation, for the uses and purposes therein
set forth.

   GIVEN under my hand and notarial seal this 31st day of January, 2003.

                                      /s/ Lorena Patino
                                      ----------------------
                                           Notary Public

My commission expires on the 14th day of June 2006

                                       33
<Page>

STATE OF ILLINOIS     )
                      ) ss.
COUNTY OF COOK        )


   I, Mary R. McCarthy, a Notary Public in and for said County and State
aforesaid, DO HEREBY CERTIFY that RICHARD H. PROKOSCH, a Vice President of U.S.
Bank National Association, a corporation organized under the laws of the United
States of America, and FRANK P. LESLIE, III, a Vice President of said
corporation, who are both personally known to me to be the same persons whose
names are subscribed to the foregoing instrument as such Vice President, and who
are both personally known to me to be a Vice President of said corporation,
appeared before me this day in person and severally acknowledged that they
signed, sealed and delivered said instrument as their free and voluntary act as
Vice President of said corporation, and as the free and voluntary act of said
corporation, for the uses and purposes therein set forth.

   GIVEN under my hand and notarial seal this 30th day of January, 2003.

                                      /s/ Mary R. McCarthy
                                      ----------------------
                                           Notary Public

My commission expires January 31, 2005

                                       34
<Page>

                                   SCHEDULE A

                      EASEMENTS AND OTHER INTERESTS IN LAND

     1. All rights of way, easements, franchises, licenses, permits, privileges,
leases, leaseholds and other authority granted to the Company for the purpose of
constructing, installing, operating, using, maintaining, renewing, replacing or
relocating gas mains, pipelines, services and other facilities on, over or in
private property owned by others and situated in the County of Cook in the State
of Illinois, including, without limiting the generality of the foregoing, those
certain easements granted to the Company by the grantors hereinafter named and
filed for record and recorded as hereinafter set forth, to wit:

<Table>
<Caption>
                                                                                 PERMANENT             DATE
                                                         FILE      DOCUMENT        INDEX                OF              DATE
                    GRANTOR                             NUMBER      NUMBER         NUMBER            INSTRUMENT       RECORDED
                    -------                             ------     --------      ----------          ----------       --------
<S>                                                     <C>       <C>           <C>                   <C>          <C>
Midwest Generation                                      1663      None                                12/15/99     Not Recorded

Illinois International Port District                    1664      None                                10/25/99     Not Recorded

Chicago Park District See Easement No. 880              1665      00699536      20-33-303-004,        6/13/00      09/08/2000
                                                                                20-33-303-006

Release of Easement from Commonwealth Edison            1666      00699537                             9/8/00      09/08/2000

Release of Easement                                     1667      None                                10/5/00      Not Recorded

Luther Burbank Elementary (Public Building Commission)  1668      00966946      13-32-125-040-0000    9/29/00      12/08/2000

PERC Peoples Calumet, LLC                               1669      00794123      Portions of:          10/2/00      10/11/2000
                                                                                26-06-428-005,
                                                                                26-06-428-006,
                                                                                26-06-428-011,
                                                                                26-06-428-019

COSTCO (MCL)                                            1670      0010084294    14-30-400-073-0000    1/26/01      01/31/2001

Wisvest Corp. (Calumet Energy Project)                  1671      0010335148    26-19-101-001,        2/21/01      04/24/2001
                                                                                26-19-101-040,
                                                                                26-19-101-004

Wisvest Corp. (Calumet Western Railway)                 1672      None                                6/30/00      Not Recorded

Nextel Leased Site                                      1673      0010076878    17-05-306-007,        11/29/00     01/30/2001
                                                                                17-05-306-012,
                                                                                17-05-306-014

First Bank and Trust Co. (Greedwood Associates)         1674      0010335133    25-02-102-016         11/3/00      04/24/2000

State of Illinois Medical District Commission           1676      00656538      14-30-400-073-0000    8/24/00      08/24/2000

Shelly Friedman (Popeyes/Taco Bell)                     1677      0011020450    13-30-409-014-0000    8/24/01      10/1/2001

Jewel/Osco (Illinois Medical District)                  1678      None                                8/14/01      Not Returned

Combined Development Howard                             1679      Not On File                         9/18/01      Not On File

Riverview at River East                                 1680      0020058271    17-10-221-004,        10/25/01     01/15/2002
                                                                                17-10-221-011

West Bradley Place (2500 W. Bradley Place)              1681      0010293443    13-24-207-019-0000    2/16/01      04/11/2001
                                                                                (part of)

8560 S. Cottage Grove                                   1682      0020947122    20-34-413-039,        7/11/02      Not Returned
                                                                                20-34-413-031

Belt Railway Company                                    R248      None                                 9/6/00      Not Recorded
</Table>

                                       35