OF THE SPECIFIC GRAVITIES OF BODIES. 191 



grains, and the avoirdupoise pound 7000 ; and hence, I-ECT. 

 the avoirdupoise dram weighs 27.34375 grains, and the ^^-s^, 

 avoirdupoise ounce 437.5. 



Because it is often of use to know how much any 

 given quantity of goods in troy weight do make in avoir- 

 dupoise weight, and the reverse, we shall here annex 

 two tables for converting these weights into one ano- 

 ther. Those from page 147 to page 158 are near enough 

 for common hydraulic purposes ; but the two following 

 are better, where accuracy is required in comparing the 

 weights with one another : and I find by trial, that 175 

 troy ounces are precisely equal to 192 avoirdupoise 

 ounces, and 175 troy pounds are equal to 144 avoir- 

 dupoise. And although there are several lesser integral 

 numbers, which come very near to agree together, yet I 

 have found none less than the above to agree exactly. 

 Indeed 41 troy ounces are so nearly equal to 45 avoir- 

 dupoise ounces, that the latter contains only 71 grains 

 more than the former : and 45 troy pounds weigh on)y 

 7ft drams more than 37 avoirdupoise. 



