AIR PUMPS AND APPARATUS. 209 



flat, and has a brass plate also truly ground to cover it, 

 having a hole in the centre with screw, to which one end of 

 an elastic tube or hose is fixed ; the other end of the tube 

 being connected with the hole in the centre of the pump 

 plate. The air being then exhausted from the tube, the 

 piston with the weights will be raised the whole length of 

 the cylinder. The number of pounds that can be raised, 

 may be ascertained by multiplying the number of square 

 inches contained in the area of the cylinder by fifteen. The 

 iron legs unscrew for convenient transportation. 



Price, with 3 inch cylinder, $6.00. 



" 31 " " $8.00. 



" best flexible tube with 



screw connectors, $2.50 to $3.50. 



Large Weight Lifter. (Fig. 209, page 210.) The con- 

 struction of this instrument is nearly the same as the preced- 

 ing, but of a larger make ; the cylinder is twelve inches 

 long and four inches wide, mounted on a strong mahogany 

 frame over five feet high. To the piston is attached by a 

 leather strap, a large platform, on which any convenient 

 weight may be placed. The instrument being capable of 

 raising over one hundred pounds. 



Price, complete, with best English flexible 



tube, 3 feet long, $15.00. 



Brass Barrel Weight Lifter. (Fig. 210, page 210.) This 

 consists of a brass cylinder, or barrel, about two and a half 

 inches in diameter, and eight inches long, open at the bottom, 

 and screwed to a mahogany frame by a flange around the 

 lower end of the cylinder, within which there is a solid 

 piston, having a stout rod which is bent in the form of a 

 hook at the end, to which a heavy weight may be attached ; 

 the upper end of the cylinder has a brass cap and stop-cock, 

 to which a flexible tube, proceeding from the air pump, may 

 be attached ; on exhausting the air, it will be found, that 

 the atmosphere pressing on the under side of the piston will 

 raise it, and a weight of about fifty pounds. 



Price, $7.50. 

 18* 



