Читать книгу The Writings of Thomas Jefferson, Vol. 6 (of 9) - Томас Джефферсон, Thomas Jefferson - Страница 11

Monticello, October 10, 1811.

Dear Sir,—According to promise I send you our observations of the solar eclipse of September 17th. We had, you know, a perfect observation of the passage of the sun over the meridian, and the eclipse began so soon after as to leave little room for error from the time-piece. Her rate of going, however, was ascertained by ten days' subsequent observation and comparison with the sun, and the times, as I now give them to you, are corrected by these. I have no confidence in the times of the first and ultimate contacts, because you know we were not early enough on the watch, deceived by our time-piece which was too slow. The impression on the sun was too sensible when we first observed it, to be considered as the moment of commencement, and the largeness of our conjectural correction (18´´) shows that that part of the observation should be considered as nothing. The last contact was well enough observed, but it is on the forming and breaking of the annulus that I rely with entire confidence. I am certain there was not an error of an instant of time in either. I would be governed, therefore, solely by them, and not suffer their result to be affected by the others. I have not yet entered on the calculation of our longitude from them. They will enable you to do it as a college exercise. Affectionately yours.