492 Proceedings of Royal Society of Edinburgh. [sess, 
3. The Iceland-spar camera had a quartz objective of 1*8 inch 
aperture, achromatised for the violet rays by a meniscus of Iceland- 
spar. As this instrument was designed for photographing the 
ultra-violet spectrum of the chromosphere and prominences, the use 
of glass (so highly absorbent of ultra-violet light) was inadmissible. 
The prism was therefore made of Iceland-spar, the material for 
which we fortunately had at the Observatory. Prof. Tait kindly 
lent us the quartz lens, and also provided the spar from which the 
compensating lens was cut. The prism and compensating lens 
were figured by Bernard Halle of Steglitz, who is specially skilled 
in working the more intractable crystalline substances. Our full 
programme included nine pictures with this camera. It was 
conveniently mounted as a partial counterpoise to the 6 -inch 
equatorial. 
4. The Dallmeyer eclipse camera of 4 inches aperture and 33 
inches focus was intended for photographing the sun’s direct image. 
The lens, which is of unsurpassed quality, was most successfully 
used by Mr Henry Davis at Baikul, Southern India, in 1871, on 
behalf of Lord Crawford. This camera was mounted on a separate 
equatorial stand provided with driving-clock and finder. Provision 
was made for fifteen exposures of various lengths. 
5. The whole-plate camera of 1J inch aperture was attached to 
the 6-inch stand, and it was intended that one plate should be 
exposed for the whole time of totality ; in this way, though the 
plate would be over-exposed for the inner corona, we hoped to 
obtain a picture of the fainter outlying coronal streamers. The 
angle covered by the lens is 44 degrees. 
All the instruments were mounted at Blackford Hill and care- 
fully tested in the beginning of July, so that everything was in 
complete order by the 11th, when they were sent off in advance of 
the party. The members of the expedition were Mr A. J. Bamsay, 
Assistant Astronomer ; Engineer M‘Pherson, our invaluable fac- 
totum; my son Theodore (who accompanied us as a volunteer), 
and myself. 
On July 18 we sailed from Newcastle to Bergen, proceeding 
thence by the Norwegian mail to Vaclso, where we arrived on the 
28th. As we were the first astronomical party to arrive, we had 
practically the choice of positions, and with the friendly help of 
