EXPLANATION OF EXAMPLE 13.

On page 118 of the Nautical Almanac, January 8th, the moon's upper transit at Greenwich is 12h 39m, which shows that the moon passes the meridian of Greenwich on the 9th (civil time) Oh 39m A.M. Then the astronomical date would be expressed as 7d 11h 51m, from which subtract the correction 18m for longitude 9 hours east, and gives the moon's upper transit at Port Darwin. To this add the high water interval, 4h 57m, and the result will be the astronomical date and time of high water, 7d 16h 30m. To this add 1 day and subtract 12 hours to convert the astronomical time into civil time the 8th, 4h 30m A.M.

To the moon's upper transit at Port Darwin, 7d 11h 33m, add the low water interval, 11h 18m, which gives the astronomical date and time of low water, 7d 22h 51m. To this add 1 day and subtract 12 hours to convert the astronomical time into civil time the 8th, 10h 51m A.M.

From the same page of the Almanac take the moon's lower transit for the 7th, 7d 23h 27m, from which subtract the correction 18m for longitude 9 hours east, which gives the moon's lower transit at Port Darwin, to which add the high water interval, 4h 57m, and the result will be the astronomical date and time of high water, 8d 04h 06m, and being less than 12 hours is also civil time P.M.

To the moon's lower transit at Port Darwin, 7d 23h 09m, add the low water interval, 11h 18m, and the result will be the astronomical date and time of high water, 8d 10h 27m, and being less than 12 hours is also civil time P.M.

13. Example: January 8, 1917. Find the times of high waters and low waters at Port Darwin, Australia.

EXPLANATION OF EXAMPLE 14.

On page 118 of the Nautical Almanac, January 23rd, the moon passes the meridian at Oh 22m after noon and would be expressed as 23d 00h 22m, from which subtract the correction 16m for longitude 8 hours east, which gives the moon's upper transit at Cape Lambert. To this add the high water interval, 11h 30m, and the result will be the astronomical date and time of high water, 23d 11h 36m, and being less than 12 hours is also civil time P.M.

To the moon's upper transit at Cape Lambert, 23d 00h 06m, add the low water interval, 5h 10m, and the result will be the astronomical date and time of low water, 23d 05h 16m, and being less than 12 hours is also civil time P.M.

From the same page of the Almanac take the moon's lower transit for the 22nd, 22d 11h 52m, and from it subtract the correction 16m for longitude 8 hours east, which gives the moon's lower transit at Cape Lambert, and to this add the high water interval, 11h 30m, and the result will be the astronomical date and time of high water, 22d 23h 16m. To this add 1 day and subtract 12 hours to convert the astronomical time into civil time the 23rd, 11h 06m A.M.

To the moon's lower transit at Cape Lambert, 22d 11h 36m, add the low water interval, 5h 10m, and the result will be the astronomical date and time of low water, 22d 16h 46m. To this add 1 day and subtract 12 hours to convert the astronomical time into civil time the 23rd, 4h 46m A.M.

14. Example: January 23, 1917. Find the times of high waters and low waters at Cape Lambert, Australia.