Page:Proceedings of the Royal Society of London Vol 69.djvu/278

262 further helped by three non-commissioned officers who had volun- teered to assist in the eclipse observations. The entire party was arranged as follows :

Personnel.

Mr. A. Walter : Newbegin photo-visual telescope, 71 inches focus.

Bombadier A. H. Thome : Recorder to Mr. Walter.

Mrs. Walter Maunder : Dallmeyer Stigmatic lens twin camera, 9 inches focus.

Sergeant J. H. Tyson : Recorder to Mrs. Maunder.

Lance-Corporal A. Balgue : Waters camera, 8 feet equivalent focus.

Mr. G. H. Ireland : Kinematograph. The kinematograph gave no result, the film tearing across before totality was reached.

(Mr. Ireland brought a camera of about 2 feet focus, which was mounted as a stationary camera, and six exposures were made with it by Mr. T. W. Harming.)

I add here a brief description of the photographs obtained :

1. The Dallmeyer Stigmatic Twin Camera.

These lenses are each 1|-. inches aperture, 9 inches focus, and give a field nearly 40 " in diameter on a plate 16 cm. square. I procured one of these lenses in 1897, on account of its great field, in order to photo- graph the Milky Way, and it being the only photographic lens I then possessed, I took it to India in 1898. Exposures of 20 seconds made with it upon the corona of that year, recorded the coronal extensions much further from the Sun than they had been photographed before ; in one instance to a distance of 13'9 lunar radii from the Sun's centre. My purpose on this occasion was to repeat the Indian exposures of 20 seconds, and also to try the effect of exposures longer still. I there- fore gave two exposures with each camera one of 2 minutes and one of 20 seconds.

No. 1. From 30 seconds to 150 seconds. Exposure 120 seconds. Sandell Triple-coated plate.

A fairly dense negative. The chromosphere has come up as a very brilliant ring, but the motion of the Moon across the Sun's disc during the very considerable exposure is very apparent. Of course no detail of the inner corona is seen on such a small image, except the large prominence on the east limb of the Sun, but the outer corona is fairly defined, tapering in long rod-like rays which on the east side of the corona reach a distance from the Sun of about five lunar radii, and on the west side of about six.

No. 2. From 30 seconds to 150 seconds. Exposure 120 seconds. Imperial Special Rapid plate.

This negative is not so dense nor so well defined as No. 1. The