LONGITUDE OF McGILL OBSERVATORY. 127 



Several determinatious of the value of 1 diviisiou of the level have beeu made since the 

 instrument was mounted, giving for the mean value 1 div. = 0M31. The power employed 

 was 102. The observations for inequality of pivots indicate that they have exactly the 

 same diameter. 



Clock. — The clock employed was Frodsham 132*7. 



Chronograph. — A Bond chronograph was used. 



For a description of the instruments employed at the Montreal station, reference is 

 made to the report of Professor McLeod. 



The observing list of stars was selected with reference to the requirements stated in 

 the discussion following, but, as nearly always happens, A^arious circumstances combined 

 to prevent a close adherence to the original scheme. It was the aim to obtain, for each 

 position of the instrument, observations of at least, 



2 stars having a large south declination. 



2 stars situated near the equator. 



4 stars symetrically situated with reference to the zenith of the observer. 



2 polar stars at the upper culmination. 



2 polar stars at the lower culmination. 



The data derived from the observations are given in the following table. The appa- 

 rent right ascensions of the stars are also given. They have been taken from the Berlin 

 J:ihrbu<h for 1883. 



The following corrections derived from more recent observations have been applied : — 



Star. 



;' Hydras . . . . 



Gioombriilgc 2001 



Groombridge 2164 

 6 Draconis - - - - 

 /; Draconis - . - - 



The data derived from the observations are given on the following pages. 



