A General History and Collection of Voyages and Travels, Volume 16 eBook

Robert Kerr (writer)
This eBook from the Gutenberg Project consists of approximately 768 pages of information about A General History and Collection of Voyages and Travels, Volume 16.

A General History and Collection of Voyages and Travels, Volume 16 eBook

Robert Kerr (writer)
This eBook from the Gutenberg Project consists of approximately 768 pages of information about A General History and Collection of Voyages and Travels, Volume 16.

The penumbra was visible at least ten minutes before the beginning and after the end of the eclipse.  I measured the uneclipsed part of the moon with one of Ramsden’s sextants, several times before, at, and after the middle of the eclipse; but did not get the middle so near as might have been effected by this method.  Indeed, these observations were made only as an experiment, without aiming at much nicety.  I also measured mostly one way; whereas I ought to have brought alternately the reflected and direct images on contrary sides with respect to each other; reading the numbers off the quadrant, in one case, to the left of the beginning of the divisions; and, in the other case, to the right hand of the same.  It is evident, that half the sum of these two numbers must be the true measurement, independent of the error of the quadrant; and this is the method that I would recommend.

But I am well assured, that it might have been observed much nearer; and that this method maybe useful when neither the beginning nor end of an eclipse can be observed, which may often happen.

Immediately after the eclipse was over, we observed the distance of each limb of the moon from Pollux and alpha Arietis; the one being to the east, and the other to the west.  An opportunity to observe, under all these circumstances, seldom happens; but when it does, it ought not to be omitted; as, in this case, the local errors to which these observations are liable, destroy each other; which, in all other cases, would require the observations of a whole moon.  The following are the results of these observations: 

Myself with / a Arietis — 204 deg. 22’ 07” \ mean 204 deg. 21’ 5”
\ Pollux — 204 20 4 /

Mr King with / a Arietis — 204 27 45 \ mean 204 18 29
\ Pollux — 204 9 12 /
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Mean of the two means 204 19 47

The time-keeper, at 4^h 30’, to which time all the \ 204 04 45
lunar observations are reduced /

The current which I have mentioned, as setting to the eastward, had now ceased; for we gained but little by plying.  On the 6th, in the evening, being about five leagues farther up the coast, and near the shore, we had some traffic with the natives.  But, as it had furnished only a trifling supply, I stood in again next morning, when we had a considerable number of visitors; and we lay-to, trading with them, till two in the afternoon.  By that time, we had procured pork, fruit, and roots, sufficient for four or five days.  We then made sail, and continued to ply to windward.

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A General History and Collection of Voyages and Travels, Volume 16 from Project Gutenberg. Public domain.