4. Given Depth of Shaft AB and Dip of Vein Angle CB to find Distance BC between Bottom of Shaft and Outcrop.—BC = AC × natural sine ACB. Or by scale and protractor by inspection.
RAINFALL.
One inch of rain = 22,680 gallons, or 102·35 tons of water per acre.
NOTES ON BELTING.
Co-efficient of friction between ordinary leather belting and cast-iron pulleys or drums = ·423. Ultimate strength of ordinary leather belting = 3086 lb. per square inch. Belts vary from ³∕₁₆ in. to ¼in. thick, average ⁷∕₃₂ in.
Power of Single Leather Belts.
To calculate the power of single leather belts, the following formula may be used: Let HP = actual horse-power. W = width of belt. F = driving force. T = working tension from 70 to 150 lb. V = velocity of belt in feet per minute.
| Then F = | W × T. | HP = | V × F. | W = | 33,000 × HP. |
| 2 | 33,000 | F × V |
Example:—A 10-inch belt running 2500 feet per minute, what horse-power will it transmit? Assuming the working tension to be 100 lb.,