Mr, Woodhouse's account y &c. 
419 
purpose of finding a star's place in the meridian. Each 
circle is furnished with two verniers; one for polar, the 
other for zenith distances. 
I wish to add a few words respecting the determining the 
place of the transit room, and the adjusting the instrument to 
the plane of the meridian ; which, as we had in the begin- 
ning no astronomical point to stand on, was a matter of some 
trouble. 
Our first object was, if possible, so to fix the site of the 
transit room, that its meridian mark might be placed on the 
steeple of Granchester church, distant to the south about 2|- , 
miles from the field on which the observatory was to be built. 
The first approximations to such site were made by ad- 
justing the middle wire of a small transit telescope ( i8 inches 
long) to the spire, or iron rod of the steeple, and by com- 
paring the sun's transit with the time brought up by chrono- 
meters from Mr. Catton's observatory at St. John's College. 
Our second approximations were made by observations of 
high and low stars with the small transit instrument above 
mentioned. 
According to the results thus obtained the piers of the 
transit were placed; and when, in June 1824, the instrument 
was put upon them, were found to be placed with consider- 
able exactness. From the above time observations have 
been constantly made with the instruments described in this 
paper, and with a clock made by Molyneux and Cope. 
The first operation was to determine the clock's rate, 
which was done by observations of the same stars on succes- 
sive days : the next, to determine the clock's error, which 
was found in the usual way, by deducting the observed 
MDCCCXXV. 3 I 
