186 SPECIFIC GRAVITY. 



NOTE. To find the number of cubic inches in any irregu- 

 lar body, weigh a vessel containing sufficient rain water to 

 cover the solid, then immerse the solid in the water by 

 means of a string or wire held in the hand, being careful 

 not to touch the vessel. While the solid is immersed, 

 weigh the water and vessel again ; the difference will be 

 the weight of the water displaced by the solid. 



RULE. I. Multiply the weight of the water in ounces by 

 1728, and divide by 1000, the result will be the contents in 

 cubic inches. 



II. To find the weight, multiply the weight of the water 

 displaced in ounces by the weight of a cubic foot of the 

 substance, and divide the product by 1000, and the result 

 will be the weight in pounds. 



I have a pattern of a lock that will displace 20 ounces 

 of water ; how much will 1000 copies of cast iron weigh ? 

 How much will they cost me at 9 cents per pound ? 



oz. 



OPERATION. 20x450 JH- 1000= 9.01 Ib. 



lb. 



9.01 x 1000 x 6.09=$810.90. Ans. 



I have a lead pattern of a wheel that displaces 15 ounces 

 of water ; what will 500 copies in brass cost me at 40 cents 

 per pound ? 



oz. 



OPERATION. 15 x504f ^-1000=7.571 lb. 



7.571 x 500 x $.40 =$15 14. 20. Ans. 



