HOROLOGY* 
time-keepers have of late been brought to very great per- 
feftion, yet I think it mult be admitted, that they are 
fufceptible of dill greater improvement; and, confidering 
the amazing fervice they have rendered to navigation, 
every pofiible encouragement ought to be given to ren-> 
der them Hill-more lerviceable. 
“ The fcapement is compofed of two diftindt parts of 
aftion. Fil'd, that which the wheel ’locks, or refts upon, 
while the balance is in motion ; and, fecondly, that which 
gives the impuife to the balance after it is unlocked ; 
and thofe that are. made with the lead friction are un¬ 
doubtedly the bed. The contrivance of locking the 
wheel on a faring, if properly made, is I think as perfeft 
as human invention can produce; but the mode of giv¬ 
ing motion to the balance I by no means think is lb; 
for, when you compare the manner in which the balance 
of a watch.is kept in motion with the pendulum of a 
clock, you mud give the preference to the latter. The 
former, moving on oppofite centres, as foon as they come 
in contact, oppofe each other, till they come into a ftraight 
line, and in leaving each other occafion confiderable fric¬ 
tion up the fide of the tooth, which aftion, not accord¬ 
ing with the motion of the balance, greatly retards its 
progrefs. 
“The maimer in which the pendulum of a clock is 
kept in motion is very did'erent; for, as foon as the wheel 
is unlocked,, it receives the impuife from what is called a 
crutch, which, being fufpended on the lame parallel of 
fufpenfion, deferibes exaftly the fame circle, and confe¬ 
quently there cannot be the fmalled friftion whatever. 
After many and various trials which I have made to pro¬ 
duce the fame principle in watches as is_in clocks, I 
found I could not give the impuife from its.own centre 
without introducing other pieces which would counteract 
the good effeft derived therefrom ;• neverthelefs I was de¬ 
termined to approach as near to it as pofiible, and to em¬ 
ploy no more parts to produce the effect, than are ufed 
in thofe of the common condruCtion. In order to do 
this, I made a horizontal contrate-wheel, and cut teeth 
on the uppermod rim of it; I introduced a piece of brafs 
infide it, jud free of its bottom, on which I placed, half¬ 
way between the extremities and the centre of the wheel, 
the axis of the balance, on which I put a round piece of 
fteel with a notch in it, called the- impulfe-pallet, and nearly 
half the fize of the wheel’s diameter. After the wheel is 
unlocked in the ufual way, with a fpring, the pallet re¬ 
ceives a .tooth on the point of the notch, which forces it 
round in a circular direction nearly correl'ponding with 
its own; confequently, there cannot be fo much friCtion, 
as the teeth do not take above half the ufual depth into 
the impulfe-pallet, in which cafe jewelling will be quite 
unneceflary; the machines muft lad longer, and, as good 
performance depends on the uniform motion of the ba¬ 
lance, there is not the fmalled doubt but, if judice is done 
in executing the other parts of this fcapement, and a 
proper compenlation for heat and cold, they will perform 
more accurately than any that have been hitherto invent¬ 
ed; but, in cafe any doubt fliould arife on my plan of 
placing the impulle-pallet in the midway between the 
extremities of the wheel and its centre, F beg leave to of¬ 
fer this fingle proportion; the propriety of which will 
not admit of the fmalled doubt, viz. If it be perfection 
to give motion to a body acting on pivots from its own 
centre; the nearer you approach to that centre, the lefs 
friCtion there will be.” 
Fig. 95 is a perfpeftive view of Mr. Watkins’s fcape- 
nient. A, the circular frame of the machinery. B, the 
balance-fpring. C, the balance. D, the axis, or verge. 
E, the cock in which the upper pivot of the axis runs. 
F, the impelling-pallet, on the axis of which is a fmall 
unlocking-pallet. G, the detent and unlocking-fpring. 
H, the axis of the fcape-wheel, fupported by a cock be¬ 
low it. ■ I, the fcape-wheel. K, the cock which fupports 
the lower axis of the balance and fcape-wheel. L, the 
threw for adjtiding the locking of the wheel. Fig. 96 is 
a bird’s-eye view of the fame, wherein A is part of the 
circular frame of the machinery. C, the balance. M, the 
fmall unlocking-pallet, above the impelling-pallet (F, fig. 
95.) G, the'detent and unlocking-fpring. I, the fcape- 
wheel. K, the cock which fupports the axis of the ba¬ 
lance and fcape-wheel. L, the fefew and fmall cock for 
adjuding the locking of the wheel. , 
Mendliam's Improvement of Mudge. —The filver medal of' 
the Society of Arts was voted in 1805 to Mr. Mendham 
of Counter-dreet, Borough, for this improvement, of 
which the following is his defeription. Fig. 97 reprefents 
the fcapement without the red of the train; a a are the 
two plates of the frame between which the train runs ; 
b, is the lad or balance-wheel of it, with teeth nearly 
fimilar to that of the balance-wheel of an eight-day clock, 
moving with the flat face of the tooth forward againd- the 
pallet c of an upright fpindle d ; e is a locking-fpring 
nearly fimilar to a detached one, having no extra fpring to 
pafs to and fro. with. Above'the pallet c, is a very fmall 
one, f, which is for the purpofe of unlocking the wheel, 
which is better fhown in fig. 98 ; at the lower part of the ' 
fpindle d, is a hair-fpring g, fo pinned as to bear the pal¬ 
let f againd the locking-fpring with fufheient power, lb 
that of its own accord it frees the wheel, and lays the pin. 
h, which comes through the plate, gently up to the dop,. 
confequently the tooth falls upon the pallet c, but fo 
clofe home to the' centre of the fpindle, that it has no 
power to pafs it of its own accord; the pin h is fixed to 
the top extremity of the pallet c, and riles perpendicularly 
through the plate a fome way above the furfhee. The 
balance i is fixed on the centre of its fpindle, principally 
on account of equalizing the weight, befides which it is 
the mod convenient to be fo; it is fupported between the- 
plate a and the cock k, precifely over the fpindle d ; corr- 
fequently the action of each is in the fame arch, and the 
connexion is between the pin h of the pallet and the pin. 
/ of the balance, (a pin fixed in the balance at the fame- 
didance from its centre as the pin h is from the centre of 
the fpindle d , and fufficiently long to touch the pin h fide- 
ways ;) there is therefore no frift ion whatever between, 
them. 
Having mentioned the diderent parts of the fcapement, 
I fliall proceed to explain its’ aftion. The immediate 
courfe of vibration is from the fpring g ; the balance-fpring 
is fo placed that the pin / of the balance ftands near the 
pin h of the pallet; it is tO' be remembered that the tooth 
of the wheel reds on the pallet during the vibration of 
the balance, fo that, when the balance is put in motion, 
the pin l comes in contaft with the pin k, which dand's 
perpendicularly and carries it back; as loon as moved, the 
tooth of the wheel gives it an extra abidance of about 
one-fifth of a circle, pafles, and lays the next tooth on 
the lock; on the return of the balance, the fpring g ap¬ 
plies all its power in urging the' balance forward till it 
comes to the dop; the balance then maintains its motion, 
and, the fmall pallet f having unlocked the wheel, the 
tooth falls again on the great pallet c, and waits the re¬ 
turn of the balance. The balance carrying the piece k 
back, forms a mod admirable banking without any extra 
apparatus, which is generally done by fome kind of dop 
on the hair-fpring, which mud have an irregular effeft.. 
The farther the pin is carried back, the dronger the 
fpring operates againd it; and, from the extent where the 
piece may be forced back to, there is play for near two 
whole circles of vibration, without any pofiibility of up- 
fetting. The balance of the model vibrates about a cir¬ 
cle and one third, with extraordinary freedom, through a 
train of four wheels and a large heavy balance, with only 
the power of a dout watch-fpring. I therefore think the 
power neceffary to carry a train with this fcapement, may 
be confiderably lefs than any other of a detached nature. 
Fig. 98 reprefents the axis d fhown feparately, in order 
that the arm and pin k, and little pallet f, may be feen 
more didinftly. Fig. 99 is the balance-wheel b, and a few 
of its teeth, jud to fhow the method of locking and un- 
3 locking. 
