LXXII ROYAL SOCIETY OF CANADA 
etc., it is not necessary to speak of here at length. The operation of the 
whole system has been very satisfactory. 
4. Geophysics. 
In a room provided for the purpose in the basement is placed a 
Bosch seismograph. Two horizontal pendulums are set on a pier inde- 
pendent of the walls of the building, and their oscillations are recorded 
on sensitized paper at a distance of some 4 metres, by light reflected 
from small concave mirrors set over the fulcrum points of the pendu- 
lums. The paper is moved by clock work at the rate of 90 em. per 
hour. The record is graduated by interruptions in the continuous trace 
of the spot of light, which are effected every minute by a shutter 
operated on the minute dial circuit. 
A half-seconds pendulum apparatus, of the Mendenhall pattern is 
used for gravity observations in the field. Field magnetic instruments 
comprise a magnetometer and dip instrument of the Eschenhagen type, 
a Fraser magnetometer, Kew Dip Circle, etc. No magnetic observations 
are taken at the Observatory; that is precluded by the nature of the 
building. 
5. Miscellaneous. 
The photographic room is 43 by 17 feet, well lighted by a large 
window and skylight at the north end. At the southern end of the 
room a short flight of stairs leads to the dark rooms, including the 
developing room and an enlarging room. A camera carrying a plate 16 
by 20, and used for copying plans, is placed in the lower room. In the 
enlarging room is a camera for daylight work adjustable to any desired 
scale of enlargement up to five times. A lantern is provided for enlarg- 
ing by artificial light, but it is seldom used, the daylight being found 
preferable. The principal use of the apparatus is for the enlarging of — 
negatives taken by surveyors in the field for topographical purposes; the 
usual scale for these enlargements is two diameters, the negative 434 
by 612 inches giving a print 914 by 13. 
A workshop, in the basement, is fitted with a universal milling 
machine, an engine lathe and a bench lathe, besides all necessary appli- 
ances and tools for metal working. Power for the machines is got by 
a motor from the city lighting circuit. The workshop is a very useful 
adjunct to the Observatory. The spectrograph for radial velocity deter- 
minations referred to above, has been constructed there, and many 
minor jobs of construction and repairs have been executed. 
6. Trigonometrical Survey. 
A triangulation is in course of execution covering the country 
between the St. Lawrence and Ottawa Rivers, eastward from near the 
longitude of Ottawa towards the junction of the rivers, thence to be ex- 
