As the moon is less than 90° from the sun this correction is also negative, or
We have now the necessary elements in the Nautical Almanac, which we must reduce for the instant of the vortex passing the meridian in Greenwich time.
| Meridian passage, | local time, at | 9h. | 5m. | A. M. |
| " | in Greenwich time | 2d. | 3h. | 1m. |
| Right ascension | same time | 56° | 42′ | 45″ |
| Declination north | " | 18° | 00′ | 1″ |
| Obliquity of the vortex | " | 26° | 2′ | 32″ |
| Polar angle | " | 18° | 5′ | 7″ |
| Arc AQ | " | 26° | 51′ | 4″ |
| PA | = 17° | 59′ | 59″ | } | P | = | 128° | 37′ | 38″ |
| PV | = 26° | 2′ | 32″ | ||||||
| VA | = 89° | 3′ | 0″ | V | = | 47° | 59′ | 44″ | |
| VQ | = 62° | 11′ | 56″ | A | = | 20° | 3′ | 42″ | |
| PQ | = 47° | 14′ | 22″ | Q | = | 26° | 22′ | 55″ | |
| Latitude of Q on the sphere | = | 42° | 45′ | 38″ | |||||
CORRECTION FOR PROTUBERANCE.
We have hitherto considered the earth a perfect sphere with a diameter of 7,900 miles. It is convenient to regard it thus, and afterwards make the correction for protuberance. We will now indicate the process for obtaining this correction by the aid of the following diagram.