$86 An Account of the Measurement 
Carr. I should not omit mentioning in this article, that while 
the instrument was at Clifton, the direction of the meridian 
was obtained from numerous observations on the pole star, at 
the times of its greatest eastern and western elongations from 
the meridian. It will be recollected, that similar observations 
were made at the station on Dunnose, in 1793; (see Phil. Trans, 
for 1795, page 460;) so that nothing relating to the terrestrial 
part of the operation remained to be performed at the expiration 
of 1801. 
On my arrival in town, after the measurement of the base of 
verification in the north, I had the happiness of finding the 
zenith sector nearly completed. Little remained to be done, 
besides the dividing of its arch; an operation which Mr. Berge 
proposed to defer till the following spring ; it was then divided, 
and the instrument, being otherwise complete, was delivered into 
my hands in April. An observatory of convenient form having 
been previously made, the sector was immediately erected in the 
Tower; and, from thence, with the permission of Dr. Maske- 
lyne, it was sent to the Royal Observatory at Greenwich. 
It is now necessary I should enter into a minute detail of this 
instrument’s construction, giving a description of its several 
parts, with references to proper drawings. If, indeed, I had no 
other motives, I should perhaps be induced to do it from justice 
to the merit and memory of the ingenious inventor; who seems 
to have exerted his talents to the full extent of the hopes he 
entertained, of rendering this instrument the first of its kind. 
General Description of the Zenith Sector. 
In the sector I am going to describe, Mr. Ramsden has ob- 
viated the inconveniences attendant on the use of former sectors ; 
