LIT THE ROYAL SOCIETY OF CANADA 
use. A new reflecting device for bringing the opposite limbs of the 
sun together on the slit has been applied. 
One of the problems in this connection is whether the rotational 
velocity varies for different lines of the spectrum, and a preliminary 
investigation on the accidental and systematic errors to be expected 
in this regard was undertaken. Much experimenting along the line 
of the best photographic conditions (kind of plate, development, etc.) 
for the regions of the spectrum undertaken, À 5500 À 5700, and À 4220 
to À 4280, was also done. The work of obtaining and measuring plates 
for the solar rotation is now well under way. 
A substantial recognition of the standing the Observatory has 
already obtained was shown at the meeting of the Solar Union, above 
referred to, by the appointment of its representative, Mr. Plaskett, on 
three important committees on solar and stellar research. 
Piers for the two meridian marks of the transit circle, with pro- 
vision for underground reference marks, were built last summer. Tem- 
porary wooden sheds were put up over them, pending erection of the 
permanent buildings which is expected this year. The underground 
lenses and the long focus collimating lenses, with the necessary mount- 
ings, have been ordered. Improvements have been made in the 
mounting of the microscopes of the transit circle and in the illuminating 
apparatus. The ventilation of the room has been improved by the 
use of ventilating fans, but it is still found that the temperature within 
does not satisfactorily follow that of the outside air, and further im- 
provements in ventilation are in contemplation. Regular observations 
of right ascension were begun in March, 1910; some 5,000 transits 
have been observed. Zenith distance observations were begun last 
January. Investigations have been made of the errors of bisection 
in star and collimation observations. 
The Bosch photographic seismograph has been in constant oper- 
ation during the year. To one of the pendulums magnetic damping 
has been applied by means of a powerful horse-shoe magnet. The 
other pendulum retains the air damping. The air damping is service- 
able in recording the microseisms; the magnetic damping reduces the 
effect of these, and thereby allows the various phases of the greater 
disturbances to be more surely identified. 
Earthquake bulletins are issued regularly, which are sent to earth- 
quake stations over the world, in exchange for their bulletins. This 
Observatory has been the first on this continent to issue regular bul- 
letins. Twenty-four have been issued during the year, giving records 
of 89 earthquakes, and have been distributed to 55 stations. No 
earthquakes occurring in Canada have been recorded. 
For the better interpretation of the seismograms by differentiating 
disturbances not of seismic origin, a Fuess electric recording anemo- 
te 
