CLOCK. 



wheel 96. In the wheel 64 eight of its 

 teeth correspond to one of the pins for 

 the hammer, and as the pinion of the 

 wheel o has eight teeth, it (wheel o) will 

 turn once for each stroke of the hammer. 

 By the remaining wheels, one, o, multiply- 

 ing six, antl the other,/*, eight times, the 

 fly will turn 6 X 8 = 48 times for one 

 turn of o = one stroke of the hammer. 

 Fig. 3. is also mechanism relating to the 

 striking part: r is a small pinion of one 

 tooth, called the gathering pallet, on the 

 arbor of wheel o, and consequently turns 

 once for each stroke of the hammer ; s is 

 a segment of a large wheel which it turns 

 (called the rack) ; t is an arm attached 

 to the rack, whose end rests against a 

 spiral plate V, called the snail; this is 

 fixed on the tubular arbor before describ- 

 ed of the hour hand and wheel 72, and 

 turns round with it once in 12 hours. 

 The plate is divided into 12 equal angles, 

 30 degrees each, and as it turns, each of 

 these answers to an hour ; the circular 

 arcs forming the circumference of the 

 snail are struck from the centre of the 

 arbor between each division with a differ- 

 ent radius, decreasing a certain quantity 

 each time in the order of the hours. The 

 circular part of the rack -s is cut into 

 teeth, each of which is of such a length, 

 that every step upon the snail shall an- 

 swer to one of them ; to is a spring press- 

 ing against the tail of the rack, and act- 

 ing to throw the arm of the rack against 

 the snail; g is a click, called the hawk's 

 bill, taking into the teeth of the rack, 

 and holding it up in opposition to the 

 spring w : i k is a three-armed detent, 

 called the warning piece ; the arm k is 

 bent at its end, and passes through a 

 hole in the front plate of the clock, so as 

 to catch a pin placed in one of the arms 

 of the wheel p, fig. 2, and which de- 

 scribes the dotted circle in fig. 3 ; the 

 other arm i stands so as to fall in the 

 way of a pin in the wheel 40. In the 

 present position of the figure, the wheels 

 of the striking train are in motion, and 

 would continue turning until the gather- 

 ing pallet r, whicli turns once at each 

 stroke of the hammer, by its tooth lifts 

 the rack s in opposition to the spring w 

 one tooth each turn ; and the hawk's bill 

 rr retains the rack, until a pin in the end 

 of the rack is brought in the way of the 

 lever of the gathering pallet r, and stops 

 the wheels from turning any further: it is 

 in this position with the rack wound up, 

 till its pin arrests^he tail r. that we shall 

 begin to describe the operation of the 

 striking of the clock. The wheel 40, as 



we have said before, turns once in an 

 hour, and consequently at the expiration 

 of every hour the pin in it takes the end 

 ?', and moves it towards the spring near 

 it ; this depresses the end k until it falls 

 in the circle of the motion of the pin in 

 the wheel p, fig. 2, at the same time the 

 short tail depresses one end of the hawk's 

 bill, and raises the other g-, so as to clear 

 the teeth of the rack s ; immediately the 

 spring to throws the rack hack, until the 

 end of its tail t touches that part of the 

 snail which is nearest it ; when the rack 

 falls back, the pin in it is moved clear of 

 the gathering pallet r, and the wheels set 

 at liberty; the maintaining power puts 

 them in motion ; but in a very short time 

 before the hammer has struck, the pin in 

 the wheel p falls against the end of k, and 

 stops the whole ; this operation happens 

 a few minutes before the clock strikes, 

 and this noise of the wheels turning is 

 called the warning : when the hour is ex- 

 pired, the wheel 40 has turned so far as 

 to allow the end of i to slip over its pin, 

 as in the figure ; the small spring press- 

 ing against it raises the end fc so as to be 

 within the circle ot the pin in the wheel 

 />, fig. 2 : every obstacle is now removed, 

 and the wheels run on the pinion ; the 

 wheel 64 raises the hammer r, and it 

 strikes on the bell, the gathering pallet r 

 takes up the rack, a tooth at each turn, 

 the hawk's bill g retaining it until the 

 pin in the rack comes under the gather- 

 ing pallet r, and stops the motion of the 

 whole machine, till the pin in the wheel 

 40 at the next hour takes the warning 

 piece i k, and repeats the operation we 

 have now described. As the gathering 

 pallet turns once for each blow of the 

 hammer, and its tooth gathers up one 

 tooth of the rack at each turn, it is evi- 

 dent the number of teeth the rack is al- 

 lowed to fall back limits the number of 

 strokes the hammer will make. This is 

 done by the rack's tail t resting on the 

 snail ; each step of the snail answers to 

 one tooth of the rack, and one stroke of 

 the hammer ; at each hour a fresh step 

 of the snail is turned to the tail of the 

 rack, and by this means the number of 

 strokes is made to increase one at each 

 time from one to twelve. 



CiocK-worfc, in the limited meaning of 

 the word used by artists, denotes only 

 the machinery employed in the striking 

 part of a clock ; that used for giving mo- 

 tion to the hands being called watch- 

 work. In its more extensive sense, it is 

 generally understood to mean any combi- 

 nation of wheel-work, for any purpose,, 



