Page:Proceedings of the Royal Society of London Vol 69.djvu/280

264 No. 6. Exposed at 200 seconds. Exposure about ^ second. Imperial Fine Grain plate.

A good image, not very dense, showing the middle corona and polar rays well.

3. The Newlegin Telescope.

This lens is a Cooke photo-visual objective of 4 inches aperture and 71 inches focus. The photographs were taken on quarter plates. They form an exceedingly fine series of fourteen, taken on different makes of plate and with differing exposures. They bear magnification well up to the limit we have yet tried, namely, to one giving 4 inches to the Sun's diameter. Every photograph in this series was successful.

No. 1. Exposed 7 seconds after commencement of totality. Exposure instantaneous. Plate, Lumiere Orthochromatic, Series A.

This is a not very dense negative, and shows the prominences on the east side of the Sun, and the very complicated structure of the corona surrounding them. From the large prominence on the Sun's east equa- torial limb two very marked and irregular black rifts or streaks cross the coronal wing and seem to broaden as they get further away from the Sun. A similar single streak leaves the Sun's surface to the south of the large prominence in the south-east.

No. 2. Exposed at 21 seconds after commencement of totality. Exposure, 2 seconds. Plate, Imperial Fine Grain Or- dinary.

A denser negative than No. 1, showing great extension of the polar rays. In the northern polar rays is seen a forked dark marking cutting the rays obliquely.

No. 3. Exposed at 32 seconds after the commencement of totality. Exposure 4 seconds. Plate, Imperial Fine Grain Ordinary.

The dark marking in the north polar rays is clearly seen. There is a greater extension on the north-western side of the corona than in the two previous photographs.

No. 4. Exposed at 45 seconds after commencement of totality. Exposure 6 seconds. Plate, Imperial Fine Grain Ordinary.

The corona is distinctly larger than on the previous photographs, and the dark marking cutting the north polar rays is very clearly seen.