Page:Travels to Discover the Source of the Nile - In the Years 1768, 1769, 1770, 1771, 1772, and 1773 volume 1.djvu/76

lx rack-work, and the last Mr Short ever made, which proved a very excellent instrument; also an achromatic telescope by Dolland, nearly equal to a three-feet reflector, with a foot, or stand, very artificially composed of rulers fixed together by screws. I think this instrument might be improved by shortening the three principal legs of it. If the legs of its stand were about six inches shorter, this, without inconvenience, would take away the little shake it has when used in the outer air. Perhaps this defect is not in all telescopes of this construction. It is a pleasant instrument, and for its size takes very little packing, and is very manageable.

brought home both these instruments after performing the whole journey, and they are now standing in my library, in the most perfect order; which is rather to be wondered at from the accounts in which most travellers seem to agree, that metal speculums, within the tropics, spot and rust so much as to be useless after a few observations made at or near the zenith. The fear of this, and the fragility of glass of achromatic telescopes, were the occasion of a considerable expence to me; but from experience I found, that, if a little care be taken, one reflector would be sufficient for a very long voyage.

Paris I received a time-piece and a stop-watch made by M. Lepeaute, dearer than Ellicot's, and resembling his in nothing else but the price. The clock was a very neat, portable instrument, made upon very ingenious, simple principles, but some of the parts were so grossly neglected in the execution, and so unequally finished, that it was not difficult for the meanest novice in the trade to point out the