GREENWICH OBSERVATORY. 
269 
interference with the primary objects of the institution. From 
first to last Greenwich has been held to be an institution for 
the pursuit of mensurative astronomy with utilitarian ends, and 
its instruments, and, to some extent, its personnel , have been 
provided and organised accordingly. The succession of Royal 
Astronomers — Royal Observators, as they are officially styled — 
Flamsteed, Halley, Bradley, Maskelyne, Pond, and the present 
occupant of the office, have, with one exception, laboured with 
a consistency truly remarkable, like one long-lived man, to carry 
out, with the best resources of their times, the strictly funda- 
mental works committed to them : with what results we shall 
presently see. 
Positions of stars for the formation of catalogues of star- 
places, and positions of the sun, moon, and planets for the 
ultimate formation of tables of their motions, are the staple 
observations at Greenwich, and they consist almost entirely of 
meridian observations, namely, times of transit over the meri- 
dian, for determination of objects’ Right Ascensions, and mea- 
sures of the angular distances of the same objects from the 
celestial pole, for the determination of their North Polar dis- 
tance ; these last being also made on the meridian. The instru- 
ments for these observations are the “ Transit ” and some form 
of Circle,” both instruments moving in the plane of the 
meridian only, and the first having it accurately defined by a 
vertical wire, in modern times a cobweb thread. Flamsteed 
at first had a make-shift sextant, with which he could only 
measure one star from another in a straight line, and he had to 
leave these measures to be ultimately referred to fixed points 
for determination of Right Ascensions and Polar Distances. 
But in 1689, thirteen years after his appointment, he procured 
— from his own resources, by the way, for from first to last he 
never had a penny for instruments from the Government — a 
large graduated arc, which was fixed upon a wall in the meri- 
dian plane, and upon the centre of which was pivoted a tele- 
scope with a vertical wire at its focus ; and he took clock- 
times of transit across this wire for Right Ascension, and read 
the position of the telescope upon the arc for Polar Distance. 
Halley had a transit instrument, with a 1 j-inch object-glass, 
generally similar in plan to those of the present day, specially 
for R. A. observations, and a meridianal quadrant of 8 feet 
radius specially for those in Polar Distance. Bradley at first 
had Halley’s instruments, afterwards a better transit of 2f-inch 
aperture, and a second quadrant, so that he could command 
the whole meridian from the North horizon to the South. 
Maskelyne used Bradley’s instruments from first to last, but 
the defects of a quadrant, in its liabilities to distortion and 
errors of centering, were so obvious to him, that just before his 
