INSTRUMENT FOR CdUNTINC THE LIFTS PROM A MINE« {JQ 



Fig. 2. G. The large wheel laft mentioned : it has eighty Inftrument for 

 , . counting the 



*®^^"- lifts from a 



H. A fmaller wheel of fifty teeth, fixed fafl on the face of xni^e. 



the wheel G ; which wheel H works a wheel I, of the fame 

 number of teeth, fliown by dotted lines behind the figured 

 dial-plate. 



K. The fhort hand, or finger of the dial, is placed upon an 

 arbor or collar of this wheel I, and moves with it. 



The long finger, or hand of the dial-plate, goes upon a 

 Iquare on the end of the fpindle on which the above arbor 

 moves; which fpindle moves forward this long finger one 

 divifion in fifty of the outer circle marked on the dial-plate, 

 every time the rope, or any thing attached to it, has been 

 down to the bottom of the mine, and returned to the top. 



The inner circle of the face of the dial is marked in divi- 

 lions of fifty each. When therefore fifty draughts up and 

 down have been made from the mine, the fliorter hand will 

 be found, if both hands were originally fet correctly at the 

 top, to have moved to the firfl interior divifion marked 50; 

 and fo on, in proportion, will advance as more draughts are 

 made. 



K, Is a board placed under the wheels B D, in Fig, 1 , and 

 which feparates them from the other wheel-work in Fig. 2, 

 where only a few teeth of the wheel B appear behind it. 



L L, Show the temporary handles in both figures ; and 

 the pofition of thofe letters denote that the gudgeon of the 

 windlafs, when the machine is in adual ufe, fliould be there 

 joined to, or make a part of the roller A. 



Fig. 3, Shows, on an enlarged fcale, the form of the catch 

 C. The fleel fpring M preffing againfl the pin N, returns 

 the catch to the tooth of the wheel D, when it has been forced 

 back ; and a pin fixed underneath the catch moves in a groove 

 O, made in the wheel B, to prevent the catch being prelfed 

 too far back, or thrown out improperly by the fpring, 



A door is fixed on each fide the box, and fhould be locked, 

 to prevent the hands being altered unknowingly. 



The drawing of a machine for fimilar purpofes, intended 

 to be ufed with a gin or horfe-wheel, alluded to in Mr. Antis's 

 letter, is in the Society's poffeflion, if a reference thereto be 

 thought necelTary. 



