3834 é REPORT—1905. 
variations of X and of Y are calculated and tabulated for each hour of the day for 
the different months of the year. These are then combined into four periods— 
March-April, May-August, September-October, and November-February. 
The values of the latitudes of these three stations are added and divided by 
three, and the same is done for the longitudes; this gives the latitude and the 
longitude of a mean station whose daily variations of X and of Y at any hour are 
obtained by taking the algebraic mean of the variations at the three stations at 
the same hour. : 
The latitude and the longitude of the three stations relative to the mean station 
are then obtained, and the variations at any station for a particular hour expressed 
in an equation 
AX, = AXn +f (lat. sm) +9 (long. onl 
where AX, is the variation of X at a particular hour of Greenwich mean time at 
any station, 
AX» is the variation of X at the same hour of Greenwich mean time at the mean 
station, 
F (lat.sm) is a function of the latitude of the station with respect to the mean 
station. 
F (long. om) is a function of the relative longitude of the same station with 
respect to the mean station. 
The values of AX and of AY are then obtained at the intersection of alternate 
degrees of latitude and of longitude. 
The integral 
| Has 
taken round a closed curve then gives the value of the vertical current perpen- 
dicular to the enclosed area, which would account for the variations of the X and 
the Y as they are given by the interpolation formula. 
The value of this current is tabulated for each hour of the day, and the results 
shown in maps. 
FRIDAY, AUGUST 18. 
The following Papers were read :-— 
1. Geodetic and Gravitational Observations in Spitzbergen. 
By Dr. O.“BAcKLunND. 
2. On the Theory of Algol Variables.. By J. H. Juans. 
3. Double Star Astronomy in the Southern Hemisphere. 
By R. T. A. Innes, FP. RSL. 
This paper briefly recapitulated the work done in the past in the discovery and 
measurement of double stars in the Southern Hemisphere. The systematic double 
star survey of the Northern Hemisphere and that portion of the Southern visible 
from California, now being carried on at the Lick Observatory by Professors 
Aitken and Hussey, was referred to. The desirability of providing a telescope of 
24 or 25 inches aperture to continue this survey to the South Pole was pointed 
out. 
1 See Astrophysical Journal, September 1905. 
