The Sun.
London, England, 1850-04-12 00:00:00

INSTITUTION OF CIVIL ENGINEERS.

On Tuesday, April 9 (William Cubitt, Esq., Pre-
sident, in the chair), the paper read was "On the
Construction of Locks and Keys," by Mr. J. Chubb,
Assoc. Inst. C. E.

The author commenced by stating, that the most
ancient lock, of whose form and construction there was
any certain knowledge, was the Egyptian, which had
been in use for upwards of four thousand years. The
construction of this lock was minutely described,
also that of the ancient " warded " and " letter "
locks, and considerable antiquarian research was dis-
played in tracing their origin and introduction. These
three kinds of locks were, in principle, the foundation
of all modern locks, which might be thus enumerated,
reversed, for obvious reasons, in their order of
antiquity :
First. The letter locks ; mostly used for padlocks,
and were so far convenient, as a key was not required
for opening them. A modification of this lock had
been proposed, called the " scutcheon " lock, for se-
curing doors and iron safes, but it was too expensive
and complicated to come into general use.
Second. Locks having fixed wards, in which no
real improvement had been made in modern times.
These locks were bad in principle, as they could be
easily picked ; and owing to many thousands of them
being yearly made, that could be passed by the same
key, little or no security was afforded by them ; in
fact, it might be safely asserted, that twenty skeleton
keys would open all the locks, of a given size, made
upon this principle.
Third. The Egyptian lock ; the essential principle
of which was, that of moveable pins, or studs dropping
into, and securing the bolt, all of which must be
raised to the proper height, by corresponding pins in
the end of the key; before the bolt could be un-
fastened. This lock was the foundation upon
which most of the ingenious inventions of
late years had been based, differing only
in the forms of the moveable obstructions
to the bolt,—some of which acted vertically,
others horizontally, some with a rotatory motion, and
many others in an endless variety of ways; but of all
these it was thought sufficient to describe only those
best known and appreciated, namely, Barron's, Bra-
mah's, and Chubb's.

In Barron's lock, patented in the year 1774, a great
improvement was made upon the ancient Egyptian,
by the introduction of the over-lift, wards being also
used; but, from the fact of there being only two
tumblers, it was evident that no great change or per-
mutation could be made in the combinations.
In Bramah's lock, patented in the year 1784, there
was a compound of both direct and rotatory motion
given to the key, instead of simply the latter, as in
Barron's lock. It consisted of a number of sliders,
having notches, of various depths, cut on one edge, so
that the motion 'of the bolt was totally prevented,
until each slider was pressed down to its exact depth,
which was effected by the key having six cuts in it of
different lengths.
In Chubb's lock, first patented in 1818, and since
modified and improved by various subsequent patents,
there were six separate and distinct tumblers, placed
over each other, and capable of being elevated to dif-
ferent heights, but all moving on the centre pin.
This lock differed from the others, in having a
"detector," by which any attempt to pick or open
the lock with a false key, was immediately notified
on the next application of its own key.
Calculations were then gone into to show the num-
ber of different combinations which might be made
in this lock, and it appeared that, with an average
sized key, having six steps, each capable of being
reduced in height twenty times, the number of
changes would be 86,400 ; that if the seventh
step, which threw the bolt, was taken into
account, the reduction of it only
.ten times
would increase the number to 864,000. Further,
that as the drill pins of the locks, and the
pipes of the keys, might be made of three different
sizes, the total number of changes would be 2,592,000.
In keys of the smallest siz°, the total number would
be 648,000, 'Whilst in.-those of the largest size it
would be increased to 7,776,000 change'.
In conclusion, it was stated, that the manufacture
of locks and keys was principally carried on at Wol-
verhampton and the adjacent towns, Birmingham, and
London, and that the fundamental principle upon,
which all locks should be made were perfect sem-
rity—strength, so as to resist, attempts to force them,
or of opening
by picklocks, and false keys,—simpli-
city in the arrangement, so that any stranger, having
the proper key, _
might be able to open the lock,—and
durability,

The paper was illustrated by a series of diagrams,
and a variety of specimens of the locks and keys
noticed in the paper ; and also by a number of Gothic
locks and keys of very elaborate workmanship, suit •
able fur ecclesiastical buildings, &c., from Mr. Chubb's
works in London.

Iu the discussion which ensued, many additions
were made to the historical part of the subject, and
various ingenious contrivances were described, which
had been successfully applied, to give increased
security to locks of ordinary construction. The com-
binations in the locks of Surtimerfurd and M'Kinnon
(of New York), were also fully described ; an advan-
tage being claimed for the former, in making one
tumbler to lift and the other to fall, in order to open
it ; and, for the latter, that, by the addition of a cur-
tain, of case-hardened iron, three-quarters of an inch
in thickness, radiating from the centre of the pin, and
a radiating key, there were no mpans of reaching the
tumblers, for the purpose of talking an impression, or
otherwise, except by cutting through that curtain.
On the other hand, it was positively asserted,
that no impression could be taken of, or means in-
vented for picking, a lock which had six tumblers,
although it could be easily done, with locks having
fixed wards; further, that Chubb's lock was a decided
improvement on al others of the same character,
lucfman, uiouefih) the
aan o as
d
it
consequent
a "detector," which formed
really the peculiar feature of that lock ; the excel-
lencekm workmanshipdurability, tended alsfourtowtbhiecbfait wascility
so celebrated.

The discussion upon this paper was announced to
be resumed at the next meeting of Tuesday, April
16th, when the following would be read, " Descrip•
tion of the Insistent Pontoon Bridge, erected on the
Midland Great Western Railway of Ireland, at
Dublin," by Mr. R. Mallet, M. Inst. C. E.

CHESTER AND HOLYHEAD RAILWAY..—TriIffiC for
the week ended April 7, 1850:—C. and H. Alain, Line,
1,491/. 19s. Od.; Mold, 92/. 12s. 5d.; Steam-bdats, 12E4
15s. Cd.; Total, 1,7144 Us. sd.