460 Messrs. Dobbie and Hutcheson on a Method of 



(about ^ of an inch), the other (b) of large diameter. A 

 piece of tubing c, of the same diameter as 6. and furnished 

 with a stopcock, is joined to b by means of a piece of rubber- 

 tubing g, so that it can be quickly disconnected and joined 

 again. A piece of cork or wood, d, with a groove cut in it, 

 serves as a stand for the apparatus, which is farther sup- 

 ported by the metal upright e. 



a — 



The small tube a is graduated from the point indicated on 

 the figure to cubic centimetres ( = grammes), or grains of 

 water. Several lines are engraved on the tube b, at the 

 same level as the beginning of the graduation on a. The 

 tube is filled with water up to one of these lines. The 

 substance whose specific gravity is required, having been 

 weighed, is placed in the tube b, when it of course displaces 

 its own volume of water. 



The tube c is then attached ; the stopcock is opened, and by 

 blowing through c the level of the water in b is depressed below 



