116 



EOGEES AND McLEOD ON THE 



was reversed ouly at the time of exchange; a complete set iu cue position being obtained 

 before the clock exchange, and in the other position after the exchange of signals had been 

 made. 



Stars and Star Places. 



The apparent right ascensions of the stars observed were taken from the Berliner 

 Astronoinisches Jahrbuch fur 1883. The corrections given by Professor Rogers in his report 

 were applied to the stars there named. 



Personal Equation. 



The same selection of stars was made in these observations as in the time observa- 

 tions, and each star was observed by both observers on such of the reticule groups as to 

 give arithmetical means corresponding to the mean wire. To obviate any error which 

 might arise from unequal spacing of the lines, we exchanged reticule groups in observing 

 similarly situated stars. The results of these observations are given by Professor Rogers, 

 and after arranging them according to declination, he remarks that ' ' there is a slight 

 diminution of the value of the equation (R — M) cos ô corresponding to an increase in 

 the declination of the star observed." I have found that on the average of the work at 

 both stations the observations at different declinations are made to accord fairly well when 



they are reduced to (R — M) cos î S. This is represented in the following table : — 



The mean of all the stars observed at Cambridge gives R — M = 154 sec i d, and 

 at Montreal, R — M = "130 secirJ. These values have boe)i emplojï^ed in computing 

 the personal equation correction in Table VIII. 



Computation ok Clock Errors. 



Level Errors. — The adopted values of the inclination of the axis have been derived from 

 the observed values by plotting the latter and drawing a smooth curve io pass as nearly 

 as possible through the middle points of the straight lines joining adjacent observations. 

 The observed and adopted values are entered in Table II. 



Reduction of Observations. — The method of reducing the observations was as follows : — 



