298 



Records of Measures 



593] M. 3. N airne's plates of same piece *. 

 Out of water Loss in water 



Mean 2-6779 



I cub. inc. water = -5278 oz. 

 I oz. of glass = 9-84973 cub. inc. 



[The weights in I st & 2 nd column are in ounces, pennyweights and grains 

 (Troy), in the 3 rd and 4 th in decimals of an ounce, and the 5 th is the specific 

 gravity. The number 9-84973 is the logarithm of the number of cubic inches 

 in an ounce of glass.] 



M. 4. [Gives I st the length of each side of each piece of glass, and the 

 distance between the middles of opposite sides to hundredths of an inch. 



2 nd the thickness at each corner and middle of each side to thousandths of 

 an inch. 



3 rd specific gravity and mean thickness deduced from it for plates A to M 

 of Nairne. 



The results are given in M. 5. The thicknesses are as follows: 



[The thicknesses given in Art. 324 are those calculated from the weight in 

 and out of water and the measurement of the sides. They are greater than 

 the measured thicknesses in every case.] 



594] M. 6. Measures of thickness & a of green glass cylinder. 

 Longest cylinder : a mark made with file near middle. 

 The i 8 ' column is the distance in inches of the point to which cylinder is 

 immersed in water from the scratch. 



* [Art. 314.] 



