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APPENDIX.
NO. 1.
land, and with the best instruments Europe affords, been able to make this observation of the Moon and a star with any thing like the precision required to determine the Longitude within the limits required by the Act of the 12th of Queen Anne; I know it cannot be done. Nay I further call upon any such Astronomers to declare, whether even in observations of the distance between the Sun and Moon, two of them observing together have generally speaking agreed in this observation within a minute of a degree: I know that in general the difference between the best observers even at land will be more, and as a farther proof of this assertion, I refer the reader to the note below:[1] and if these matters of
- ↑ In the fifth volume of M. de la Caille's Ephemerides, p. 31, he says, 'that any person would be in the wrong to suppose that the Longitude at sea can be determined by the Moon, to a less error than two degrees, let the method which is employed be never so perfect, let the instruments, of the sort now in use, be never so excellent, and let the observer be the most able and accomplished. For if we examine, without prejudice, all the circumstances which enter into the calculation and into the observation of a Longitude at sea, we shall be easily convinced, that it would be ridiculous to maintain, that the sum of the inevitable errors should not amount to five minutes of a degree, that is, to two degrees and a half of Longitude.' N.B. M. de la Caille published this in the year 1765, and is universally allowed to have been an excellent observer, and made several voyages by sea, where he made trials of this method by the Moon. Dr. Halley and Dr. Bevis (as appeared to the honourable House of Commons upon an examination of the latter) did,
