Page:Proceedings of the Royal Society of London Vol 69.djvu/279

Rh sky glare has come up, and the extensions are not so considerable as in the former case.

No. 3. From 170 seconds to 190 seconds. Exposure 20 seconds. Sandell Triple-coated plate.

The image of the corona is fairly dense, but the sky glare has not come up so much as in the previous cases, and it shows as great ex- tension as No. 1.

No. 4. From 170 seconds to 190 seconds. Exposure 20 seconds.

Imperial Special Rapid plate.

This is a weak image, and has no points to recommend it. (Nos. 3 and 4 have a double image on them, due probably to the cameras not having settled down after the plate-carriers were changed.)

2. The Niblett Lens.

This lens is of 4 inches aperture and 34 inches focus, fitted with a revolving drum carrying 5-inch by 4-inch plates.

No. 1. Exposed at second contact. Exposure about second. Imperial Fine Grain plate.

This photograph was taken at second contact, and several " beads " of sunlight are seen. Nevertheless, not only is there a great deal of detail to be seen in the middle corona, but on the west side a coronal ray can be traced to two lunar radii, and on the east side to a somewhat greater distance. The image is a fairly dense one. The image is not large enough, nor was the exposure sufficiently short to show any detail in the prominences or chromosphere, but the polar rays and the " combing out " of the equatorial wings are well seen.

No. 2. Exposed at 40 seconds. Exposure about second. Im- perial Ordinary plate.

A fairly dense image, showing the polar rays and middle corona well.

No. 3. Exposed at 80 seconds. Exposure about | second. Imperial Special Rapid plate.

The image is not so dense as in the previous cases, but the coronal rays can be traced to a greater distance, as can also the polar rays.

No. 4. Exposed at 120 seconds. Exposure about second. Imperial Special Rapid plate.

A weak faint image, under-developed. No detail shown.

No. 5. Exposed at 160 seconds. Exposure about second. Imperial Ordinary plate.

Under developed, only the chromospheric ring seen.