Pocketbook of Useful Formulæ and Memoranda
for Civil and Mechanical Engineers

85 OF ENGINEERING FORMULÆ. Blasting. L = Least line of resistance in feet. X = Number of ounces of powder required to blast any rock when L = 2 feet. P - Quantity of powder in ounces required. „ XL3 Then P = , Q L3 Or when X = 4 ounces, P = • Li L should not exceed | depth of hole. Table of Charges w hen X = 4 ounces. Charge of powder. K Charge of powder. feet. 1 2 3 4 lbs. oz. 0 1 . 0 4 0 134 2 0 feet. 5 6 8 lbs. 07.. .3 14| 6 12 16 0 In small blasts 1 lb. of powder will loosen about 4Å tons. In large blasts 1 lb. of powder will loosen about 2f tons. . One man can bore from 50 to 100 inches per day in granite, or 300 to 400 inches per day in limestone.