232 
PROCEEDINGS OF SECTION A. 
on either side of the opening which lies at the bottom of the depres- 
sion between the ridges. To avoid confusion, it may be mentioned 
that the small circular building in the foreground is a detached hut 
containing a 12-inch reflector. 
A covered way, some 80 feet in length, connects the transit- 
house with the western tower of the main building. In the lower 
story of this tower will be placed a four- fold chronograph for general 
use, each of its barrels being capable of recording some six hours’ 
work. The room next above will contain charts and a small reference 
library for the use of the observer who is in charge of a 24-inch equatorial 
reflector housed in the revolving drum which caps the tower. As 
may be seen from the picture, this drum or dome is completely finished, 
as far as the outer appearance goes. It was constructed by Sir 
Howard Grubb, of Dublin, and is 22 feet in diameter. The frame- 
work and shutters are of steel, covered first with wood and then with 
copper. The photograph scarcely gives an adequate idea of the 
elegance and harmony of this structure ; the well-known green of the 
oxidised copper blending most exquisitely with the pale pink of the 
Doddington sandstone used in the masonry, and the more delicate 
tracery of the pilasters and mouldings giving an exquisite finish to 
the whole. The cylindrical form of roof was chosen as offering the 
greatest facility for use in a variable climate. Nothing, indeed, can 
surpass its convenience as planned by the distinguished Irish engineer. 
The thumb and finger suffice to impart a rapid rotation to the whole 
roof. A single pull on a cord withdraws the side shutter into a 
pocket in the wall of the drum ; hence all possibility of the unpleasant 
or dangerous rattling of the open shutter in a gale of wind is obviated. 
More than half the hemisphere of the heavens is now open to the 
observer, while he, as well as his instrument, are sheltered 
from any sudden downpour of rain. In case of very high wind, a 
revolving steel shutter can be pushed upwards to any desired 
height, short of obstructing the view, to exclude the violent 
eddies of the wind so disastrous to observations. The root* shutter 
“telescopes” in two parts, and can consequently be withdrawn 
considerably beyond the zenith without projecting at the back of 
the dome, where it might easily be injured by a strong wind. It is 
obvious that the roof shutter need only be withdrawn as much as is 
required by the position of the object under study or the necessities 
of thorough ventilation. Prom the chart-room of the western tower 
we step out on the asphalted platform connecting the two towers. 
The most beautiful panorama of Edinburgh lies before us — from the 
Salisbury Crags to the Corstorphine Hills, with the castle rising 
grandly in the centre. This platform is more than 100 feet in length 
by fully 20 in breadth. Erom one part or other practically the 
whole of the sky can be scanned, as an extension to the south in the 
centre allows the observer to move out of the line of the domes. 
"When the photograph was taken, near the end of October, 1894, the 
workmen were still engaged on the eastern dome. Now that it is 
nearly finished, it can be seen that it will be fully as ornamental as its 
neighbour. It will contain the 15-inch achromatic refractor from 
Dunecht, a telescope as complete in its appliances as any in existence ; 
being provided with electric control, slow motions from the eye-end, 
micrometer with independent illumination of right-ascension and 
