Orr, M. A. (Mary Acworth) · London and Edinburgh, Gall and Inglis · leaf 147
ey had many ways of measuring their distances andmotions, and even the angular sizes of sun and moon, andtheir instruments were the forerunners of our sextants,micrometers, and transit instruments, our chronometersand sidereal clocks. The gnomon has been already described^, and itwas one of the… … 25 -S 3 ^ ^ THE SCHOOL OF ALEXANDRIA. 115 as fine as the eye of a needle: the observations madewith this were much more exact than observationsof the end of the shadow, which must always be vague,and the Chinese records of the suns movements madewith this instrument between 1270 and 1280 A.D. areof…
Dante Alighieri, 1265-1321 · Astronomy, Ancient · Astronomy, Medieval · Early maps
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