128 DESCRIPTION OF A LARUM FOR A WATCIf. 



ing screw to the back of the quadrai'.t; the staff K is screwed 

 into the above socket. 



jF^o*. V shows the pi:actical method of using the instru- 

 ment for determining the distances of the objects Q end R 

 from the two stations S and T, at which the instrtiment is to 

 be successively pkiced, and used as before described. 



Fi^, VI is the diagram referred to at page 220. 



Fig. VII represents the mode of applying the tightenii)^ 

 screw H, In Fig. I and iV, by means of the seiuicircuiar 

 spring, enclobjng the cylindrical stem, or neck of tiie joint. 



Description of a Larvm appUcahle to any Pocket Watch, hy Mr» 

 John Prior, oflSessJield, near Skipton, in Craven*, 



Ap-licdble (o JL N constructing this machine, I have endeavoured to makfg 



w mut niur- ^* ^^ simple as I could ; so that by the assistance of a pocket 



iug it, wrtrh, of any size, or any number of turns of the fusee, 



which ever way it is wound np, it will cause the larum to let 



go at any time required, without hurting the going of the 



watch. 



New method In winding up the main-spring of this machine, I have 



", ^"''.'"^ "^ u?ed a niethod different from that of an v other person, and 



I lie "lain- " ^ 



spring, which adrhits of Its acting with considerably more power than 



where thicker pivots are used, 

 and >topping it The discovery of stonping the main-spring when wound 

 with.uta ^jp witbrnt a fusee, I must beg leave to say, gives me a 



great deal of satisfaction; and will, I hope, be useful to my 



brother workmen. 



To show with what ease a watch will turn the larum screw, 



I made the following exp' -iinent. 

 Ease with When the machine was wound up and the lever put u|)0i^ 



which it acts, j^^ screw, I turned the a\is of the screw, while one o^ the 



pins, which has a communication with the key when the 



** The Society of Arts voted Mr. Prior their silver medal and twer ♦; ^ui- 

 lU'jii; for thi^ iiiYcntiou. Traus, Vol. XXIII, p. ;39.3. 



match 



