2^0 DESCRIPTION OF A lAEUM OF A WATCH. 



eight hours, do not turn it back, but put the lever into th* 

 second turn of the screw ; and so for the rest. 



I am, Sir, 



Your very humble servant, 



JOHN PRIOR. 



Reference to the Engraving of Mr, Prior' slL^arunu PL VL 

 Explanation of pig. \ shows a bird's-eye view of the machine, 

 t e p ate ^^ shows the position of the watch on the larum. 



B. The spiral cylinder, fixed on the axis, and moved by a 

 pm across a key placed on the fusee square of the watch. 



C. The acting lever, one end of which lies upon the spiral, 

 the other end is movable upon an arbor D. 



E, shows a notch cut in the arbor D. This notch is cut 

 more than half through the arbor, in a situation opposite to a 

 pin at F, in the middle of the rim of the larum contrate 

 wheel G. When the lever C falls off the cylindrical spire 

 B, the notch E is moved to a situation so as to allow the pin 

 F to pass through the notch which discharges the larum 

 hammer H, which works by pallets in the contrate wheel G 

 in the usual manner* 



O. The barrel which contains the spring, the inner hand of 

 which is connected with the same axis as the contrate wheel. 



K. The finger piece which winds up the spring. 



h, b, b. The three sliding pieces which hold the watch. 



e, c. Two projecting pins, which are carried round by the 

 pin d, which is fixed across the key fitted to the fusee. 



Fig, 2 shows that side of the machine on which the watch 

 is fixed. 



a. The sliding piece, on which the pendant of the watch 

 is hung. 



b, b, b, The three sliding pieces which serve to adjust the 

 watch, and hold it in such a position that the fusee square 

 maybe in a line with the axis of the spiral cylinder B, 

 slwwn in Fig. 1. 



1 is a ratchet wheel, on the centre of which is a button or 

 finger-piece K, to wind up the larum spring. 



L. The 



