None
0 i 2 3 4 5 6 7 8 9 10 ii In. AZIMUTH TABLE XIX. —CONSTANTS. Number. Logarithm. Ratio of circumference to diameter Base of hyperbolic logarithms 3-I4I59 2 71828 0.49715 o 4.^4.20 Modulus of common system of logs Length of seconds pendulum at N. Y. (inches) o. 43429 3Q. IOI7 9.63778-10 i. 50220 Acceleration due to gravity at N. Y Cubic inches in i U. S. gallon 32-15949 231. I- 50731 2. 36361 Cubic feet in i U. S. gallon o. 1337 9 12613—10 U. S. gallons in i cubic foot . .. 7. 4805 o. 87303 Pounds of water in i cubic foot Pounds of water in i U. S. gallon Pounds per square inch due to i atmos.. .. Pounds per square inch due to i foot head of water 62.5 8-355 14.7 o 4.34. 1.79588 0.92195 1.16732 Q. 6374Q—IO Feet of head for pressure of i pound per square inch 2 3O4 o. 36248 Inches in i centimeter o. 3037 O. 5CKI7— IO Centimeters in i inch Feet in i meter 2.5400 3.2808 0.40483 o. 51598 Meters in i foot o. 3048 9. 48402-10 Miles in i kilometer o. 62137 9- 79335~ID Kilometers in i mile I . 60935 o. 20665 Square inches in i square centimeter.. .. Square centimeters in i square inch. . .. Square feet in i square meter 0-155° 6.4520 10. 764 9. 19033-1° 0.80969 i. 03197 Square meters in i square foot Cubic feet in i cubic meter 0.09290 35. 3156 8.96802-10 i. 54797 Pounds (av ) in i kilogram 2 2046 O. 34333 Kilograms in i pound (av ) o 4=136 o. 6^667—10 Ft -Ibs in i kilogram-meter 7. 23308 O. 8^032 Natural sine of o° oo' 01" = .00000485; log Natural sine of o° 01' = .00029089; log Natural sine of o° i' Natural sine of o° oo' 01" 4-68557 6.46373 0.03 ft. 100 ft. 0.3 inch i mile MISCELLANEOUS RULES 73 MISCELLANEOUS RULES. To reduce a slope measurement to horizontal when the vertical angle is given: Add the log vers of the angle to the log slope distance. The sum is the log correction. Subtract the correction from the slope distance. To reduce a slope measurement to horizontal when the difference in elevation of the ends of the tape is given: Divide the square of the height by twice the slope length and subtract the result from the slope length. EXAMPLE. Height, 8.1 feet, slope length, 85 feet. (8.i)2 -j- 170 = 0.38. Horizontal distance = 84.62 feet. If the height is large compared with the distance make a second com putation, dividing the square of the height by the sum of the slope length and the approximate horizontal distance. Use this correction instead of the first. EXAMPLE. Height, 20 feet, slope length, 100 feet. (20)* -=- 200 = 2.00 feet. Approximate horizontal distance = 98.0 feet. (2o)2 -r- 198.0 = 2.02. Horizontal distance = 97. 98 feet. Correction in feet for effect of earth's curvature and refraction equals •ffo feet times the square of the distance in statute miles. To obtain the approximate difference in elevation in feet from two readings (in inches) of an aneroid barometer: T. TT T Diff. Elev. = 55,000 X T 77 H th Part o* th^s difference for every degree that the mean temperature of the air exceeds 55° Fahren- heit. H and h represent the two readings in inches. EXAMPLE. Lower Station 30.57 inches 40° Fahr. Upper " 30.05 " 36° " Difference .52 " Mean 38° " Sum 60.62 " v$fo x 55°°° = 472 feet ?Vff x 472 = l6 Temperature Corr. = — 16 " Difference in Elev. = 456 " UNIVERSITY OF CALIFORNIA LIBRARY BERKELEY Return to desk from which borrowed. This book is DUE on the last date stamped below. ASTRC NDMY LIBRARY LD 21-100m-ll,'49(B7146sl6)476 YB 75046 m. 