Improvements in Gas Engines.
Year: 1899

page_text: Date of Application, 10th Oct., 1899-Accepted, 10th Feb., 1900
Improvements in Gas Engines.
I, GEORGE CROYDON MARKS, of 18, Southampton Buildings, Chancery Lane,
London, W.C., Consulting Engineer and Chartered Patent Agent (a communi-
cation from John Potter Murphy, of Aldine Hotel, Philadelphia, Pennsylvania,
United States of America) General Superintendent, do hereby declare the nature
of this invention and in what manner the same is to be performed, to be particu-
larly described and ascertained in and by the following statement:-
My invention relates to the construction of gas engines and has for its object
the general improvement of engines of this kind, the leading feature of my "in-
vention consisting in a novel combination of a four cylinder engine with a two
crank shaft whereby an explosion takes place for each half revolution of the shaft.
Another feature of my invention consists in a novel valve or valve and igniter
mechanism characterized by great simplicity and applicable with advantage to
two cylinder engines, although especially adapted for the four cylinder type. Still
another feature of my invention consists in a novel device for governing the action
of the admission valves. I have also in the development of my engine made im-
provements in the starting mechanism, in the igniting mechanism, in the construc-
tion and combination of the shaft, fly wheel and shaft bearing and in various other
parts of the mechanism as will be hereafter pointed out in the description and
claims. Reference being now had to the drawings in which my invention is
illustrated.
Figure 1 is a plan view of my engine as especially designed for use in automo-
bile vehicles.
Figure 2 is a side view of the starting mechanism.
Figure 3 is an end view of the engine.
Figure 4 is a side elevation of the engine on an irregular section line, the
general direction of which is indicated at 4-4 Fig. 1.
Figure 5 is a sectional view of one end of the shaft and the appliances con-
nected therewith.
Figure 6 is a similar sectional view of the other end of the shaft.
Figure 7 is a cross-section on the line 7-7 of Fig. 6.
Figure 8 is a cross-section on the line S-S of Fig. 6.
Figure 9 is a cross-section on the line 9-9 of Fig. 5.
Figure 10 is a cross-section on the line 10-10 of Fig. 5.
Figure 11 is a view of the engine head casting taken on the section line 11-11
of Fig. 12.
Figure 12 a view of the same casting taken on the line 12-12 of Fig. 11.
Figure 13 a view of the same casting taken on the line 13-13 of Fig. 14.
Figure 14 a view of the same casting taken on the line 14-14 of Fig. 13.
Figure 15 is a view of the valve actuating cam box with its top or lid removed.
Figure 16 is a cross-section through this box on the line 16-16 of Fig. 15.
Figure 17 is a cross-section on the line 17-17 of Fig. 16.
Figure 18 is a view on an enlarged scale of the cam actuating shaft and govern-
ing rod

page_text: Figure 19 a cross-section on the line 19-19 of Fig. 18.
Figures 20 and 21 are views showing the form and disposition of the six cams
used in my engine to actuate the admission and exhaust valves and the igniters.
Figures 22 is a side view of one of the valve actuating levers such as are used
for actuating the admission and exhaust valves.
Figures 23 a cross-section on the line 23-23 of Fig. 22, and
Figures 24 and 25 are side elevations of the cam actuating levers used in
operating the igniters.
A A A² and A3 are the four cylinders of my gas engine which may he con-
veniently formed in a single casting, as shown, and which may be surrounded
with water jackets. The cylinders A and A2 are indicated in Fig. 1 and the
cylinders A and A³ in Fig. 4 and it will be understood that the cylinder A² lies
back of the cylinder A just as the cylinder A3 lies back of the cylinder A¹ B B¹
B and B are the pistons working in the four cylinders. C is the crank shaft
of the engine, having formed upon it two cranks indicated at C1 and C2 arranged
opposite, say at 180° one to the other. Pivotally connected with the pistons B B¹
B2 and B are the connecting rods D D1 D2 and D³ of which the rods D¹ and D
are connected directly to the shafts C² and C' respectively, while the rods D³
and D³ are pivotally connected with the rods D1 and D respectively, the con-
nections being as shown at D5 and D4, Fig. 4. and it will be obvious that owing
to this construction the pistons B and B will move always together and in the
same direction while the pistons B and B² will also move together in the opposite
direction to the first mentioned couple. E indicates the fly wheel of the engine
which I have shown as constructed in accordance with another invention for which
I have also filed application for Letters Patent No. 20324 of 1899, that is to say
as provided with a transversely moving plunger E2, Fig. 6, carrving a crank
pin E and moving in a cylinder formed in the fly wheel to which leads a chan-
nel which at the centre of the wheel communicates, as shown in Fig. 6, with
a channel e formed through the crank shaft and cranks and connecting at the
other end of the shaft, as shown in Fig. 5. through a tube G with a hollow
bracket Fofo indicating the passage in said bracket and G the pipe by which
pressure fluid is induced and exhausted from the fly wheel. Referring still to
Fig. 5 it will be seen that the channel c is enlarged as indicated at 4 and still
further enlarged, as indicated at 5, the outer portion of this enlargement being
threaded, as indicated at 6, while the outer end of the shaft is continued as a
threaded projection c. The tube G which screws at one end into the head of
the bracket F10 has a portion G which fits in the cylindrical enlargement
formed as shown with a multiplicity of annular grooves which serve the function
of and take the place of packing in preventing leakage. The tube is also formed
with a shoulder G2 which regulates its entrance into the hollow shaft and is
held in place in the shaft by a long hollow screw G screwing into the portion of
and having the head g. This last described construction is also a portion of the
subject matter of my said other case and need not be further referred to.
Returning to the shaft end which is connected with the fly wheel and which is
best illustrated in Fig. 6, it will be noticed that the fly wheel E is formed with
a central projecting stud shaft E3 having near the wheel a threaded perforation E
which near the outer end of the said shaft opens into an enlarged unthreaded
perforation E. It will also be noticed that the end of the shaft Centers the
portion fitting therein and is provided with a threaded extension C which
screws into the threaded perforation E, thus uniting the fly wheel and shaft
securely together. F is the casing thrown around the cranks and the end of the
cylinders and in which the bearings for the crank shaft are formed, but the
bearing F shown in Fig. 6 I make so as to be directly a bearing for the stud
shaft E3 of the fly wheel and only through this stud shaft a bearing for the end
of the crank shaft. In this way I carry the weight of the fly wheel directly on
the bearing instead of making the bearing act directly upon the end of the shaft
and carrying the weight of the fly wheel on the shaft. As shown, I form in

page_text: the bearing F an annular chamber which communicates with a shaft starting
extension having formed in it a chamber F for a screw geared wheel and a
bearing through which the shaft passes to enter and be united with the said
wheel. is a worm wheel secured directly on the stud shaft and an en-
gaged worm wheel secured on a shaft K2 which is rotated by the rotation of the
stud shaft E and which by a universal joint, as indicated at 3, Fig. 1 or by any
other convenient mechanism, communicates rotary motion to the cam shaft k
to be hereafter described. The upper bearing for the shaft K is indicated at F,
Fig. 1. The bearing F6 (see Figs. 1 and 5) like the bearing F is preferably made,
as shown in Figs. 5, 6 and 8, that is to say, the bearing in the casing is provided
with a liner and the shaft or stud shaft as the case may be provided with a
similar liner f while a nest of rollers 18 is placed between these liners, making
the bearings both of the kind known as roller bearings.
I have already referred to the bracket 1 and will here call attention to the
fact that it is, as shown in Figs. 1, 3 and 5, an arm of a branch F secured to
the casing F by means of a flange f and having, in addition to the arm F1, an
arm Fin which is formed or to which is secured a clutch ring J3 and another
arm which supports mechanism used in starting the machine, and while still
speaking of the casing of the machine I will call attention to the shaft bear-
ings F and F (see Figs. 1, 3 and 5) which support the governor actuated
shaft I¹.
Referring now to the governor, see Figs. 1, 3 and 5, H is a sleeve secured to
the shaft as by means of a key h, see Fig. 5, and having upon it projecting
arms H H arranged in two pairs and serving to support the pivots of the
governor weights 2 H which are, as shown provided with laterally extending
lugs 2 to which springs H³ H³ are connected tending to draw the weights down
into contact with the sleeve H. The weight levers of the governor are formed
with extensions H* H* which lie in slots of arms H extending out from a
grooved ring H³ supported on the sleeve H, the groove being indicated at .
An annular ring I is secured in the groove and provided with trunnion like
pins 1 I to which are pivotally connected the arms II extending from a hub 13,
see Fig. 9, which is attached to the bottom of a shaft 1 which, extending up
through the bearings F13 and F14, see Fig. 1, has attached to its upper end a
lever arm I see Figs. 1 and 3 which in turn is connected to the end of a rod 1"
which extends through a central perforation in the cam shaft K as is best shown
in Fig. 18, in which view it will be seen that the shaft K besides being centrally
perforated is formed with slots K and K through which extend keys I and 18
secured to the rod 16 and to which in turn are secured the admission cams m
and m or rather the hubs M and M on which these cams are formed. The cou-
nection of the rod I6 with the lever I is of course by means of a joint which
permits the rod to rotate in the lever as it will be understood that the key con-
nection of said rod with the shaft K is such as requires the two. to rotate
together.
one.
For the four cylinder engine, as shown in the drawings, I employ two cams to
operate the four admission valves, two other cams to actuate the four exhaust
valves and two other cams to actuate the igniters, each acting alternately on the
valves and igniters of two cylinders, the pistons of which are coupled to move as
The admission cams are, as already stated, secured directly to the keys I'
and I so that besides rotating with the shaft K they move longitudinally along
with this shaft in a direction to an extent determined by the position of the shaft
governor. The camis actuating the exhaust valves are indicated at m³ and m³,
see Figs. 15, 16, 20 and 21; their hubs M3 and M2 are secured directly to the
shaft as are also the cams m' and m³ the hubs of which, M and M³ are also
directly attached to the shaft. The cam shaft passes through a box N in which
are situated bearing rods N13 N13 etc., as shown in Fig. 17, said rods being sup-
ported in studs n n, the latter of which extends from a central web N* in the
box N and serving to support the hubs 2012 etc., of a series of twelve valve

page_text: actuating levers, arms 13 arranged in pairs and extending in opposite directions
on each side of the shaft K+, the levers 3 appertaining to the admission and ex-
haust valves are formed, as best shown in Figs. 22 and 23, with perforated
heads at their outer ends and with upwardly extending arms O2 connected
with the hub and adapted to support cam rollers as shown in Figures 15 and 16;
O and O indicating the cam rollers acted on by the admission cam m, 02 and 0³
the rollers acted on by the admission cam m¹; 0 and 05 the rollers acted upon
by the exhaust cam m³; 06 and 07 the rollers acted on by the exhaust cam m²,
and I would here call attention to the fact that I have shown the admission cam
rollers O and ( as formed and arranged so that as the cams m and m¹ move
toward the right in Figure 15 they will move out of the path of these rollers
before they move out of the path of the rollers and O2. In this way the first
effect of the governor when the engine is unduly speeded is to cut off the admission
to two of the cylinders, reducing the explosions to one for each complete revolu-
tion of the shaft and then if the speed still exceeds the normal the cams will
clear the rollers O and O2 in which case no explosive gas is admitted to any of the
four cylinders.
In order that the bearings and contacting surfaces in the chamber N may be
thoroughly lubricated an oil pump N is provided having a plunger N10 worked
from the cam shaft through a connecting rod Nand a lever N2 which latter is
preferably formed on or secured to the hub 012 of one of the levers 0. The
pump cylinder is preferably cast on the bottom of the casing N and part of a
valve box N is likewise formed thereon. The other part of the valve box is
formed as a cover N*. The valve box is formed with suction and delivery
ports N³, No controlled by valves N³, N, respectively. The suction port N,
which is preferably covered by a grating communicates with the bottom of the
chamber N, and the delivery port communicates with a vertical conduit N' from
which the oil is led through horizontal conduits N8, No, to the bearings and con-
tacting parts of the mechanism being directed thereon by nozzles n³, nº.
Referring next to the levers used in connection with the igniters; it will be
noticed in Figures 20 and 21, that the igniter cams m and m are formed with
abrupt rear shoulders and in Figs. 24 and 25 that the valve actuating levers (13
are on one side of the cam shaft provided with upwardly extending arms as (8
having a downwardly looking abrupt shoulder 8, while on the other side of the
cam shaft the upwardly extending arm () is made with an upwardly abrupt
shoulder o. It will thus be seen that the cam roller revolved to the right will,
after depressing the levers 03 successively, suddenly leave contact permitting
the lever to snap back under the impulse of the springs which are arranged to
act upon them.
I have already mentioned the perforated hub like ends 0% of the valve and
igniter actuating levers. These perforated hubs are threaded and in them serew
adjusting screws 015 best shown in Fig. 16, said screws resting on the top of
valve spindles to be hereafter described.
Of course any construction of valve may be adapted for use with my valve
actuating cams and governing device, and before describing the specific construc-
tion of the valve shown in the drawings I will pass to other parts of the machine,
the above description being sufficient to indicate the action of the governor which
is the main point to which I have heretofore referred to in these parts.
Referring now again to Figs. 1, 2, 3, 5 and 10, J is a clutch drum secured on
the shaft C and formed as shown in Fig. 10 with a multiple series of roller cham-
bers in which are situated rollers J2 J2 etc. Surrounding this clutch drum are
three hard metal rings J6 J6 etc., one connected with a stationary clutch ring J
which, as already stated, is formed in or secured to the arm F" of the bracket F
while the other two rings are secured to the angularly movable clutch rings J
and J and it will be understood.that, as clearly shown in Fig. 5, separate set of
rollers J2 is provided for each clutch ring. From the rings J and J extend
lever arms and j³ to which in turn are secured connecting-rods' J¹º and J¹¹ one

page_text: connected on each end of the central pivoted lever J13 J1 pivoted on the arm F2
at f13 and provided with a socket J1 adapted to receive the end of the lever. The
function of the clutch ring J3 is at all times to prevent a revolution of the shaft
in a backward direction while leaving it entirely free to move forward, and the
function of the clutches J and J is to move the shaft in a forward direction;
the actuating mechanism being of a pump like action and the two clutches acting
alternately on the shaft.
P is the cylinder head casting of the engine, shown in detail in Figs. 1, 4, 11,
12, 13 and 14. It is formed with four head portions a a¹ a² and a³ fitting over the
corresponding cylinders A A¹ etc. Over and around these cylinder head portions
the casting is chambered to form a water chamber P" and over the water cham-
ber the casting is divided into three chambers P2 P2 and P³ of which in the
construction P P are admission chambers and P3 an exhaust chamber. The
form of these chambers is determined largely by the symmetrical and convenient
disposition of the valves and they are formed as shown with extensions of the water
chamber P between and partly around them, sec Fig. 1. The ports through
which the explosive mixture is introduced are indicated at and the port
through which the burnt gases are expelled is indicated at . The device in-
dicated at R in Fig. 4 as connected with the exhaust port forms the subject
matter of another application and need not be further described. Admission
ports P, two in each chamber P2, extend from such chambers in tubular form
through the water chamber into each of the four cylinders and I also form
through the entire head casting four pairs of tubular passages, indicated at 16
and 17, one pair leading into each cylinder and serving for the installation and
operation of the electrical igniter to be described. and p³, best shown in
Fig. 12 are tubular bearings for the admission and exhaust valve stems and they
are preferably made to extend both above and below the top of the casting as
shown, the upper extension serving particularly to hold in place a spring. L L
etc., indicate the exhaust valves having stems while L' L' etc., indicate the ad-
mission valves having stems . To the top of each stem is secured, as best
shown in Fig. 16, a flanged cap L² beneath which and the top of the head cast-
ing P is a spring L acting to normally keep the valve seated. The ends of the
valve rods are situated in the cam chamber N which has already been described
and their disposition is such as to bring one of them beneath the end of each of
the levers, an adjusting screw 015 screwing into the heads (14 of said levers so
as to impinge directly on the end of the valve stem when the said lever is de-
pressed by its actuating cam.
The construction of the igniter is shown in Fig. 14 of the drawings and as there
represented, a conducting rod Q extends through the perforation 1 being in-
sulated therefrom by non-conducting thimbles, indicated at 1010. The end of
the conducting rod Q which extends into the cylinder is provided with a curved
extension Q having a contact point gl and the other end of the rod Q which
extends into the chamber N is connected with one pole of a battery. The tubular
passage P7 is, as shown, fitted with a liner p which projects up into the cham-
ber but does not quite reach the cylinder leaving a cylindrical portion P
between the end of the liner P and the head of the cylinder. This liner is, as
shown, provided with a slot or slots 78. Fitting in the liner is a rod Q having
secured to it a key Q which fits in the slot or slots 8 and whereby the rod is
prevented from turning, and having secured to its inner end an elastic finger Q+
having a contact point q' so arranged as to come in contact with the point q₁ when
the rod Q3 is thrust inward. Also secured to the end of the rod Q3 is a piston
like extension Q6 which fits in the cylindrical end . The end of the rod Q³
which extends into the cam chamber is like the valve rods provided with a
head L and a spring L which holds the rod Q3 and its connections normally in
the position shown in Fig. 14. When however the igniter lever is actuated by
its proper cam the rod Q³ is forced inward, the piston Q leaving the cylinder p
and the two contact points q and q¹ being brought together. As soon as the

page_text: igniter actuating cam leaves contact with the lever arm upon which it operates
and which it will be recollected is shaped so that the contact is broken suddenly
the rod Q is instantly retracted with the effect of forming a spark between the
two contact points while a noisy and injurious blow is prevented by the entry of
the piston into the cylinder and the compression of whatever gas is im-
prisoned in said cylinder.
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed I declare that what I
claim is
1. A gas engine having four cylinders arranged side by side in pairs lying in
planes at right angles to the shaft and said pairs again arranged side by side so
that the cylinders lie within the corners of an approximate square, in combination
with pistons working in each cylinder, a shaft having oppositely disposed cranks
one lying opposite to each pair of cylinders, means coupling the pistons of each
pair of cylinders to the crank lying opposite to said pair so that said pistons move
in and out together, admission and exhaust valves leading to and from each
cylinder, means for operating the admission and exhaust valves of each pair
of cylinders as described so that explosions occur alternately in each cylinder of
each pair and an impulse is given to the shaft at each half revolution.
2. A gas engine having four cylinders arranged side by side in pairs lying in
planes at right angles to the shaft and said pairs again arranged side by side so
that the cylinders lie within the corners of an approximate square, in combination
with pistons working in each cylinder, a shaft having oppositely disposed cranks
one lying opposite to each pair of cylinders, means coupling the pistons of each
pair of cylinders to the crank lying opposite to said pair so that said pistons move
in and out together, admission and exhaust valves leading to and from each
cylinder, a single rotating cam shaft extending across the head of the engine
cylinders as described, rotating cams secured on said shaft one for the admission
and one for the exhaust valve of each pair of cylinders, and valve actuating
levers for each valve, said levers being arranged in pairs and to be engaged and
operated successively by the cams as described.
3. A gas engine having in combination two cylinders arranged side by side
on one side of the shaft, two pistons working therein and coupled to a single
crank, admission and exhaust valves leading into each cylinder, a hollow rotating
cam shaft having a transverse slot, as K³, formed therein, a rod I6 longitudinally
movable in the cam shaft and having a key, as I extending from it through
slot K³, a governor arranged to shift the longitudinal position of rod I", a rotating
admission cam, as M m, secured on the cam shaft and to the key I', a rotating
exhaust cam secured fixedly on the cam shaft and valve actuating levers, one
for each valve and each pair arranged to be engaged and actuated successively
by one of the cams except when the admission cam is shifted by the governor
4. A gas engine having four cylinders arranged side by side on one side of the
shaft and four pistons working therein and coupled in pairs to two oppositely
lying cranks on the shaft, admission and exhaust valves leading to and from each
cylinder, a rotating cam shaft extending across the head of the engine cylinders
as described, two exhaust valve cams secured on said shaft, two admission valve
cams rotating with but longitudinally movable on said shaft, a governor and con-
nections therefrom to regulate the longitudinal shifting of the admission cams,
two pairs of exhaust valve actuating levers each pair being arranged to be operated
alternately by a rotating cam and two pairs of admission valve actuating levers,
each pair being arranged to be alternately actuated by one of the governor con-
trolled cams.
5. A gas engine having four cylinders arranged side by side on one side of the
shaft and four pistons working therein and coupled in pairs to two oppositely
lying cranks on the shafts, admission and exhaust valves leading to and from each
cylinder, a rotating cam shaft extending across the head of the engine cylinders.

page_text: as described, two exhaust valve cams secured on said shaft, two admission valve
cams rotating with but longitudinally movable on said shaft, a governor and con-
nections therefrom to regulate the longitudinal shifting of the admission cams,
two pairs of exhaust valve actuating levers each pair being arranged to be operated
alternately by a rotating cam and two pairs of admission valve actuating levers,
each pair being arranged to be alternately actuated by one of the governor con-
trolled cams and one lever of each pair having its cam contacting end arranged
to remain in the path of the shifting cam after the cam contacting end of the
other has moved out of said path.
6. A gas engine having two cylinders arranged side by side on one side of the
shaft and two pistons arranged to move together, admission and exhaust valves
and an igniter for each cylinder, in combination with a rotating cam shaft having
secured thereon three cams, the one, as M m, operating the igniters having an
abrupt rear shoulder, two pairs of valve actuating levers one for the admission and
the other for the exhaust valves and each pair being arranged to be actuated
alternately by a single cam, and a pair of igniter actuating levers arranged to
be actuated alternately by the igniter cam and having their cam contacting ends
abruptly shouldered as described and so as to snap back when leaving contact
with the rear shoulder of cam M4 m².
7. In combination with a four cylinder gas engine substantially as described,
a cylinder head casting P having a water chamber P¹ adapted to come immediately
over the heads of the cylinders and to communicate with the water jacket sur-
rounding the cylinders, said casting having formed in it also two lateral cham-
bers P3 P3 and a central chamber I and valve ports P and P leading from said
chambers through the water chamber P and through the cylinder heads as .
described.
8. In combination with a four cylinder gas engine, substantially as described,
a cylinder head casting P having a water chamber P adapted to come immediately
over the heads of the cylinders and to communicate with the water jacket sur-
rounding the cylinders, said casting having formed in it also two lateral cham-
bers P2 P3 and a central chamber P³, valve ports P and P leading from said
chambers through the water chamber P1 and through the cylinder heads as
described, and igniter tubes P7 passing through the entire head casting.
9. In a gas engine a chamber N, in combination with valve actuating cams and
connections situated in said chamber, a pump having its suction port situated
at the bottom of chamber N and its delivery conduits provided with nozzles
adapted to throw oil over the bearings and contacting surfaces of the mechanism
in the chamber, a pump plunger actuated by the cam shaft in said chamber.
10. In a gas engine, a shaft coupled to the piston or pistons thereof in com-
bination with a clutch automatically acting to prevent backward revolution of
said shaft.
11. In a gas engine, a shaft coupled to the piston or pistons thereof in com-
bination with a clutch automatically acting to prevent backward revolution of
said shaft, a clutch or clutches arranged when operated to rotate the shaft in a
forward direction and means for operating the same.
12. In a gas engine, a shaft coupled to the piston or pistons of the engine in
combination with a clutch J automatically acting to prevent backward revolution
of the shaft, two clutches J J³ having actuated levers extending out from
them said clutches being adapted when moved in the direction of rotation of the
shaft to engage it and when moved in the other direction to disengage it, a
pivoted lever J¹³ J and connecting rods J10 J₁ coupling said lever with the
arms j
13. In a gas engine, a crank shaft in combination with a fly wheel, as E, a
hollow stud shaft E3 extending from the centre of said fly wheel, said shaft extend-
ing over and being secured to the end of the crank shaft, and a shaft bearing for
said stud shaft in the framing of the engine.
14. In a gas engine, a crank shaft in combination with a fly wheel, as E, a

page_text: hollow stud shaft E³ extending from the centre of said fly wheel, said stud shaft
extending over and being secured to the end of the crank shaft, and a roller shaft
bearing for said stud shaft in the framing of the engine.
15. In a gas engine, an electric igniter consisting of a fixed electrode, as q¹, in
.combination with a tubular passage leading into the head of the engine cylinder
and having an enlarged cylindrical end P³, an electrode rod Q3, moving in the
tubular passage P7, ad having a cylindrical enlargement Q6, adapted to fit in
cylinder P when the rod Q is in retracted position, an electrode q secured on
rod Q and adapted to contact with electrode 7 when the rod Q3 is thrust inward
and a spring for retracting the electrode rod after contact is made, all substantially
as described, and whereby the retracting rod is cushioned.
.
MARKS & CLERK,
18, Southampton Buildings, London, W.C.,
13, Temple Street, Birmingham, and 25, Cross Street, Manchester, Agents.