230 BENJ. PIKE'S, JR., DESCRIPTIVE CATALOGUE. 



Fig. 215. 



Fig. 246. Tube to shoiv the Relative Weight of Fluids. 

 YJFig. 246 consists of a glass tube, bent and graduated 

 as represented in the margin; on pouring into the 

 upright branches, equal quantities by weight of the 

 respective liquids, their relative weights would ap- 

 pear on inspection ; being inversely as the heights to 

 which they would rise in the branches of the tube. 

 The accuracy and utility of such an instrument are 

 augmented by filling the lower portion of the tube 

 \-/ with mercury, and the graduated branches being of 

 equal diameter, given weights of any liquids, which 

 would not act chemically on the mercury, will show, by 

 their respective heights on either side, how much greater 

 space an ounce, a dram, or any other quantity of one liquid 

 would take up than an equal quantity of the other ; and 

 hence it would appear how far the specific gravity of the 

 latter exceeded that of the former. 



Price, $0.75 and $1.50. 



Hydrostatic figures. (Fig. 247, opposite page.) This 

 consists of a tall glass jar, supported on a foot, and nearly 

 filled with water, or alcohol and water, to prevent its freez- 

 ing in cold weather, into which small hollow glass figures, 

 as men, a balloon and car, etc., are floated ; they are made 

 of variously colored glass and curiously ornamented ; they 

 have a small hole in the lower part, through which they are 

 partly filled with water, till they will just float in the liquid, 

 and the addition of a little more weight would cause them 



