70 THE ROYAL SOCIETY OF CANADA 
systematic difference of velocity for different elements is present in the 
Ottawa plates. The frequently opposite signs of the mean residuals 
at Ottawa and Mt. Wilson from the same lines, (those found at the 
latter place to give systematically higher or lower velocities) would 
point to the conclusion that the deviations previously found might have 
been either accidental, or more probably personal and due to the 
character of the lines. 
It gives us much pleasure to record here our appreciation of 
the interest the Director, Dr. W. F. King, has taken in this work, of the 
help he has afforded, and of his willingness to meet the many needs in 
the matter of apparatus arising in the course of the work. 
Dominion Observatory, 
Ottawa. 
