Page:Philosophical Transactions - Volume 004.djvu/62

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And after the same manner you are to seek the time by the
Watch B, when the Sun was in the South; which let be	8	38	48
But this Watch going 7. sec. a day too slow, it is retarded in 91. dayes, (from the 20th of Febr. to the 22 of May)	0	10	37
Which therefore added to the said time gives	8	49	25
That is the same time given by the Watch A. Now adding to this time of the Watches, the Æquation of the 22th of May	0	18	10
You have	9	7	35
Which is the same time of the day with that of the place, where the Watches were set when the Sun was in the same Meridian with the Ship, or where the Ship was at Noon.
	h.	min.	sec.
The difference is	2	52	25
Wherefore this last Meridian is by so much more Easterly, than the first; which being reduc'd to degrees (as hath been
	deg.	min.	sec.
formerly directed) make	43.	6	15

'Tis manifest, that by this way you find precisely enough the Longitude of the place, where you were at Noon, or the Time of the Suns being in the South: which, although it differs from the Longitude of the place, where you are when you observe the Setting of the Sun, yet you may estimate neer enough, how much you have adyanc'd, or chang'd the Longitude in those few hours, by the Log-line, or other Ordinary practises of reckoning the Ships way; or (which is the surer way) by the degrees pass'd in 24. hours by a former days Observation.

You may also, instead of observing the Suns Rising and Setting, observe the setting first, and then next morning the Rising; marking at both times the Time show'd by the Watches; and find thence, after the same manner as before, the Longitude of the place where the Ship was at Midnight.

Finally, you may also, instead of the Rising and Setting of the Sun, observe before and after Noon two equal Altitudes of the Sun, noting the time shown by the Watches, and reckoning in the same manner, as hath been said of the Rising and Setting: Yet it is to be consider'd that the Altitudes of the