NEW ROYAL OBSERVATORY, EDINBURGH. 
231 
The exact analogues are — 
tv i 4. / 7N . induction B 
Displacement ( d ) to or - 
4)7t 47 r 
Pressure to magnetomotive force 
^ . 47 r 47T 
E to - or - 
permeability /x 
and in conseq uence — 
Bate of change of pressure 
= E d 
Energy in unit volume 
=i E d 2 
to -< 
H= 
4'7T B 
to 
jj. 47 r 
^ or B= /xH 
Energy in unit volume 
1 
8tt 
.H.B 
7.— SOME NOTES ON THE NEW KOYAL OBSERVATORY, 
EDINBURGH. 
By RALPH COPELAND , Ph.D F.R.A.S., F.R.S.E., Astronomer Royal for Scotland , 
and Professor of Astronomy in the University of Edinburgh. 
After careful examination of the various heights surrounding 
Edinburgh, the committee appointed to report to the Secretary for Scot- 
land respecting the erection of the new Edinburgh Royal Observatory, 
fixed on Blackford Hill, about two miles south of the centre of the city, 
as the most suitable site. The committee was composed of the Earl of 
Crawford (chairman), Lord McLaren, Professor Taifc, the Queen’s 
Remembrancer, and the Astronomer Royal f or Scotland. The buildings 
were commenced in the autumn of 1892, and are now nearly completed. 
To render the following brief description more intelligible, a photo- 
graph showing all the Observatory buildings, apart from the dwelling- 
houses, is sent herewith. 
Premising that in the accompanying photograph the spectator is 
looking north-west, the orientation of the buildings will be readily 
understood. The structure on the left is the transit-house (not quite 
finished), the centre line of which, of course, ranges exactly north and 
south. In it will be mounted the Dunecht transit-circle of 8*6 inches 
aperture. Indeed, the piers for this instrument, and also for its 
collimators, each 6*2 inches in aperture, are already in position. In 
designing this building every care has been taken to insure uniformity 
of temperature within and without, so that the instrument shall yield 
observations as correct as if taken in the open air, while the observer 
and the apparatus are completely sheltered from the wind. To this 
end the walls and roof are of corrugated steel in two layers, with 
ample ventilation between ; besides which the outer wall is louvred, 
and to guard against the disturbing effects of radiant heat it is tinned. 
The coat of tin accounts for the white appearance in the picture. To 
prevent the escape of even slightly- warmed air-currents through the 
observing opening, the roof has two ridges running north and south, 
and is ventilated along each of these ridges at a distance of some 4 feet 
