VI. Directions for using the common micrometer, taken from a paper in the late Dr. Bradley's hand-writing; communicated by Nevil Maskelyne, Astronomer Royal, and F. R. S

Abstract

Micrometers, as first contrived, being only adapted to the measuring small angles, as the diameters of the Sun and Moon, or other planets, and taking the distance of such objects as appeared within the aperture of the telescope at the same time, were not of so general use as those which are contrived not only to answer the ends that the first inventers aimed at, but likewise, to take the difference of right ascension and declination of such objects as are farther asunder than the telescope will take in at once, but which pass through the aperture of it at different times.