3/4 
one wheel moves round irr the time of one 
i evolution of that which drives it. 
1 bus the great wheel on the fusee, having 
teeth, and driving the centre-wheel by a 
pinion of 12, must cause the Centre-wheel’ to 
move round four times in one turn of the 
Jfee, and so for all the rest, as follows : 
12) 48 (4 = turns or the centre \ 
d; 54 (9 = turns of the third f . 
6) 48 (8 = turns of the contrate C wheeL 
48 ( 8 T dims of the balance ) 
Whence it ollows, that the turns of each of 
these whee s respectively, in one turn of the 
iusee, will be had by multiplying those se- 
lovvs 4ll ° tients to S etlier successively, as fol- 
1 } J; f fusee-wheel. 
■ 4xl = 4 f £ \ centre wheel, 
!*X4X 1= 36>S< third wheel. 
t'X!'x4x 1= 238k C /contrate-wheel, 
*XSx9X4x 1=2304'^ ^balance-wheel. 
But all that has been hitherto said shews 
only the minutes of an hour, and seconds or 
quarter-seconds of a minute ; for nothing lias 
been yet mentioned relating to the mechanism 
for shewing the hour of the day. This part 
of the work lies concealed from sight, be- 
tween the upper plate of the watch-frame and 
the dial-plate. . In this work, ABC (Plate 
tig. 7.) is the uppermost side of the frame- 
plate, as it appears when detached from the 
dicd-plate : the middle of this plate is perfo- 
rated with a hole, receiving that end of the 
arbor of the centre wheel which carries the 
minute-hand ; near the plate is fixed a pi- 
nion ab of ten teeth : this is called the pinion 
of report ; it drives a wheel cd of forty teeth ; 
this wheel cd carries a pinion ef of twelve 
teeth; and this drives a wheel g h with thirty- 
six teeth. J . 
As in the body of the watch the wheels 
every where divide the pinions, here, on the 
contrary, the pinions divide the wheels, and 
by that means decrease the motion, which is 
here necessary ; for the hour-hand, which is 
carried on a socket iixed on the wheel gh, is 
required to move but once round, while the 
pinion ah moves twelve times round. To 
this end the motion of the wheel cd is | of 
the pinion ab : again, while the wheel cd, or 
the pinion ef, goes once round, it turns the 
wheel gh but j part round ; consequently the 
motion of gh is but J of J of the motion of 
ab ; but f of l = that is, the hour-wheel 
gh moves once round in the time that the pi- 
nion of report, on the arbor of the centre or 
minute-wheel, makes twelve motions, as re- 
quired. 
Clock-work, properly so called, is that 
part of the movement which strikes the 
hours, &c. on a bell ; in contradistinction to 
that part of the movement of a clock or 
watch which is designed to measure and ex- 
hibit the time on a dial-plate, and which is 
termed watch-work. The wheels composing 
the clock part are: the great or first wheel E 
(see Plate fig. 8), which is moved by the 
weight or spring at the barrel D : in sixteen 
or thirty-hour clocks, this has usually pins, 
and is called the pin-wheel ; in eight-day 
pieces the second wheel L is commonly the 
pin-wheel, or striking wheel, which is moved 
by the former. Next the striking wheel is 
the detent wheel, or hoop wheel m, having a 
hoop almost round it, wherein is a vacancy at 
CLOCK-WORK. 
which the clock locks. The next is the third 
or fourth wheel, according to its distance 
from the first, called the warning wheel, n. 
r lo these must be added the pinion of report, 
2 , which drives round the locking wheel’ 
called also the count wheel; ordinarily with 
eleven notches in it, unequally distant, to 
make the clock strike the hours. Besides 
the wheels, to the clock part belong the rash 
oi latch ; a kind ol wheel with twelve large 
langs, running concentrical to the dial wheel, 
and serving to lift up the detents every hour’ 
and make the clock strike: the detents or 
stops, which being lifted rip and lei tall, lock 
and unlock the clock in striking; the ham- 
mer, as S, which strikes the bell R ; the ham- 
mer-tails, as T, by which the striking pins 
draw back the hammers ; latches, whereby 
the work is lifted up and unlocked ; anil 
lifting pieces, as P, which lift up and unlock 
the detent O. The method of calculating 
the numbers of a piece of clock-work has 
something in it very entertaining, and at the 
same time easy and useful. We therefore 
shall here give' the rules: 1. Regard here 
needs only be had to the count wheel, 
striking wheel, and detent wheel, which move 
round in this proportion: the count wheel 
commonly goes round once in twelve or 
twenty-four hours ; the detents wheel moves 
round every stroke the clock strikes, or 
sometimes but once in two strokes : where- 
fore it follows, that, 2. As many pins as are 
in the pin wheel, so many turns has the de- 
tent wheel in one turn of the pin wheel ; or, 
which is the same, the pins of the pin wheel 
are the quotients of that wheel divided bv the 
pinion of the detent wheel. But if the detent 
wheel move but once round in two strokes of 
the clock, then the said quotient is but half 
the number of pins. 3. As many turns of 
the pin wheel as are required to perform the 
strokes of 12 hours (which are 78), so many 
turns must the pinion of report have to turn 
round the count wheel once: or thus, the 
quotient of 78, divided by the number of 
striking pins, shall be the quotient for the pi- 
nion of report and the count wheel ; and this 
is in case the pinion of report be fixed to the 
arbor of the pin wheel, which is commonly 
done. An example will make all plain : the 
locking wheel being 48, the pi- 
8 ) 48 ( 6. nion of report 8, the pin wheel 
- 78, the striking pins are 13, 
6) 78 (13. and so of the rest. Note also 
(j) 60 (10. that 78 divided by 13 gives 6^ 
6) 48 ( 8. the quotient of the pinion of re- 
port. As for the warning wheel 
and fly wheel, it matters little what numbers 
they have ; their use being only to bridle the 
rapidity of the motion of the other wheels. 
The watch part of a dock or watch is that 
part of the movement which is designed to 
ineasui e and exhibit the time on a dial-plate; 
in contradistinction to that part which contri- 
butes to the striking of the hour, &c. The se- 
veral members of the watch parts are, 1 . The 
balance, consisting of the rim, which is its cir- 
cular part ; and the verge, which is its spin- 
dle ; to which belong two palettes, or leaves, 
that play in the teeth of the crown wheel. 2. 
The potcnce, or pottancc, which is the strong 
stud in pocket-watches, whereon the lower 
pivot of the verge plays, and in the middle 
of which one pivot of the balance wheel 
plays ; the bottom of the pottance is called 
the foot, the middle part the nose, and the 
upper part the shoulder. 3. The cockJ 
which is the piece covering the balance. 4. 
1 lie regulator, or pendulum spring, which is 
the small spring, in watches, underneath the 
balance. 5. The pendulum (see Plate iw. 8) 
whose parts are, the verge, palettes°5 5* 
cocks, the rod, the fork, the flat, the bob or 
great ball, and the corrector or regulator 
being a contrivance for bringing the pendu- 
}° its nice vibrations. 6/The wheels, 
winch are the crown wheel F; in pocket- 
pieces, and swing wheel in pendulums ; serv- 
mg to drive the balance or pendulum. 7. j 
1 be contrate wheel E, which is that next the-' 
crown wheel, Ac. and whose teeth and hoop j 
he contrary to those of other wheels; whence' 
the name. 3. The great, or first wheel- 
i . ’ which is that which the fusee inline- 1 
chately drives, by means of the chain or i 
string of the spring box or barrel D ; after 1 
which are the second wheel, third wheel, Ac ' 
Lastly, between the frame and dial-plate id 
the pinion of report, which is that lixed on i 
the arbor of the great wheel ; and serves to • 
drive the dial wheel, as. that serves to carry 
the hand. The method of calculation is easily 
understood : for suppose the great wheel E 
goes round once in 12 hours ; then if it is a ' 
loyal pendulum clock, swinging seconds, we 1 
have 60 x 60 x 12== 43200 seconds or beats • 
in one turn of the great wheel : but because-! 
there are sixty beats or seconds in one mi- 1 
nute, and the seconds are shewn by an 
index on the end of the arbor of the swine'*] 
wheel, which in those clocks is an horizontal 
position; therefore it is necessary that the I 
smngoWha-l should have 60 teeth ; whence i 
= num ber to be broken into 
quotients for finding the number of teeth for 
the- other wheels and pinions. 
In the year 1803 the Society for the En- 
couragement of Arts, &c. presented to Mr. ' 
John Prior, of Nessfield, Yorkshire, a re- \ 
ward of thirty guineas, on account of his ] 
contrivance for the striking part of an eight- • 
day clock. It consists of a wheel and fly, j 
with six turns of a spiral line, cut upon tlie * 
wheel for the purpose of counting the hours. 
The pins below this spiral elevate the ham- 1 
mer, and those above are for the use of the j 
detent. This single wheel serves the pur- i 
pose of count-wheel, pin-wheel, detent- 
wheel, and the fly-wheel, and lias six revo- ’ 
lutions in striking the twelve hours. If we \ 
suppose a train of wheels and pinions used • 
in other striking parts to be made without 
error, and that the wheels and pinions would I 
turn each other without shake or play; then 
allowing the above supposition to be true ] 
(though eyery mechanic knows it is not), ' 
Mr. Prior’s striking part would be found six ^ 
times superior to others, in striking the 
hours one, two, five, seven, ten, eleven ; 
twelve times superior in striking, four, six, ‘ 
eight; and eighteen times, in striking three, 
nine, and twelve. In striking two, the in- 
ventor purposely made an imperfection equal I 
to the space of three teeth of the wheel ; and, 
in striking three, an imperfection of nine or • 
ten teeth ; and yet both these hours are ] 
struck perfectly correct. *i 
Clocks, table and rules far regulating. 
By the following table, clocks and watches 1 
