Let the latitudes, on the same side of the equator, be 10° and 60°; then the middle latitude and its complement are 35° and 55°, and half the difference of the latitudes is 25°: and the difference of longitude being 110°, the operation will stand as below.
| Log. 6600´ (in 110°) | 3.8195439 | |||
| Constant log. | -4.1015105 | |||
| -1.9210544 | ||||
| Log. sin. 35° | -1.7585913 | |||
| S = | -1.6796457 | |||
| Again | T | = 1.4281480 | ||
| m | = .4513202 | |||
| Log. (T + m) | (= 1.8794682) | 0.2740350 | ||
| Log. (T - m) | (= 0.9768278) | -1.9898180 | ||
| Log. | 0.2842170 = | D = -1.4536500 | ||
| S - D (= log. tangent 59° 16´) | = 0.2259957 |
agreeing to a minute with the solution by a table of meridional parts.
Example 2.
The rest remaining, let the difference of longitude be only 40°; then
| Log. 2400´ (in 40°) | 3.3802112 | |
| Constant log. | -4.1015105 | |
| -1.4817217 | ||
| Log. sin. 35° | -1.7585913 | |
| S = | -1.2403130 | |
| D (as before) = | -1.4536500 | |
| S - D (= log. tang. 31° 27´ ½) | -1.7866630 | |
Example 3.
Let the difference of longitude be 40°; but the latitudes 56° and 80°;
| And log. 2400´ + log. constant | = -1.4817217 | ||||
| Log. sin. 68° | = -1.9671659 | ||||
| S | = -1.4488876 | ||||
| T (tang. 22°) | = .4040262 | ||||
| m | = .2109980 | ||||
| Log. (T + m) | (= .6150242) | -1.7888921 | |||
| Log. (T - m) | (= .1830282) | -1.2625181 | |||
| Log. | 0.5263740 | = D | = -1.7212944 | ||
| S - D (= log. tangent 28° 6´) | = -1.7275932 | ||||
wanting of the true answer no more than 1° 4´.