238 



BENJ. PIKE S, JR., DESCRIPTIVE CATALOGUE. 



exactly equipoised. This effect of the vertical pressure of 

 liquids may be variously exhibited, and the results are curi- 

 ous and important. Piice, $5.00. 



Fig. 239. 



The Hydrostatic Bellows. 

 (Fig. 259.) This instru- 

 ment is sometimes called 

 the hydrostatic paradox, 

 from the fact, that a very 

 great weight may be bal- 

 anced by a small weight of 

 water. It consists of two 

 round boards, from one 

 foot to one and a half in 

 diameter, attached to one 

 another by leather going 

 all round them, and making 

 the space within them 

 water tight ; there is a hole 

 in the upper board over 

 which is screwed a metal 

 pipe, about four feet long, 

 with a funnel at the top, 

 for conveniently introduc- 

 ing water, and filling the 

 space between the boards 

 till the water stands to a 

 height of three or four feet 

 in the tube, when it will 

 sustain the weight of one 

 or two men without forcing 

 the water out. The leather 

 is stout, and prepared so 

 as to be water tight under 

 a great presure ; the tube 

 jointed that it may be more 

 portable, and also showing 

 the effect of a column of 

 water of a less height. 

 Price, $5.00. 



" extra large, $7.00. 



