186 Bond, Graham, and Peirce, on the Latitude of Cambridge. 
the transit observations, which is made in Table V., will serve to 
test the accuracy of the observations. 
The transit instrument has two very delicate levels, adapted to 
different temperatures, and each divided to seconds. 
The middle wire (D), was carefully adjusted by Mr. Bond pre- 
viously to the observations; and he could not detect any error of 
collimation, either at that time or at the close of the series. 
The telescope was mounted upon heavy stone piers, which rest- 
ed securely upon a stone foundation. 
Metnop or OBsERVATION. 
Each star was observed at its east and west transit over each 
wire of the telescope. The axis of the telescope was reversed 
every few days, which is indicated in the tabular account of the 
observations by the column which gives the position of the illu- 
minated axis as being north or south. 
The level was usually read before and after each observation, 
and was commonly reversed three or five times. About five min- 
utes were allowed, after each reversal, for the level to settle. 
Since each observation of the level often corresponded to two 
different observations of a star, it is convenient to print all the ob- 
servations of the level in the single Table III. 
The observations of the transits of the stars are given in Table IV. 
The time is that of the chronometer, No. 2419. 
Metuop or CompPurTatTION. 
Let DZD?’ be the arc of a great circle described by the axis 
of collimation of the telescope; P ZM the meridian perpendicular 
to DZD’; DMD’ the arc of a small circle described by the star. 
A and .f’ are the east and west points, at which the star makes 
