THE DOMINION ASTRONOMICAL OBSERVATORY AND THE 
BOUNDARY AND GEODETIC SURVEYS. 
Durmg the past year the work of the Observatory has followed 
the same general lines as in previous years. 
The principal work of the Astrophysical Division has been, as 
before, the determination of orbits of spectroscopic binary stars. Four 
orbits, those of 7 Camelopardalis, » Orionis, 93 Leonis and € Ursae 
Minoris, have been completed, and work on three or four others is 
approaching completion, while a good deal of preliminary observing 
and measuring has been done on several new binaries. Unusually poor 
observing weather has prevailed during the past year. This shows in 
the decrease in the average number of spectra obtained monthly from 
76 last year to 65 this, as well as in the decrease of completed orbits 
from seven to four. At the same time there is a permanent cause 
operating towards a decrease in the amount of finished work of this 
kind, in that as work progresses, fainter stars have to be observed upon, 
requiring much longer exposure time. To meet this, increase in tele- 
scopic aperture is needed, which however this Observatory is not at 
present in a position to provide for. 
No improvements in the spectrographs used have suggested 
themselves and only minor changes in the instrumental equipment have 
been made. 
The telescope has also been used in measuring the position angles 
and distances of visual double stars and in observing occultations of 
stars by the moon. 
While Halley’s comet was near the earth, photographs with the 
Brashear Doublet and with a large Zeiss Tessar lens having a field 
wide enough to take in the full distance of the tail, were obtained, 
but this work also was much hindered by unfavorable weather. 
At the meéting of the International Union for Co-operation in 
Solar Research, held at Mt. Wilson, Cal., last August, a share in the 
work of determining the solar rotation by the Doppler displacement 
of the spectral lines at opposite limbs of the sun was allotted to this 
Observatory. Considerable time has been devoted to experiments 
bearing on the best treatment of this problem. The apparatus for 
solar work, consisting of a ccelostat telescope, 80 feet focus, and a 
Littrow grating spectrograph of 23 feet focus, has been improved in 
several details., Three different gratings have been thoroughly tested, 
and the most suitable is now permanently mounted and is in regular 
