Mr. Cawthron, has already promised £30,000 to build a solar observatory in New Zealand; and the Australian Commonwealth have promised one for Australia; so that we hope the Sun will be presently under constant police supervision, and will not be able to have any disturbance of note without its being recorded.
But there is one part of the Sun which cannot be seen in the ordinary way, nor photographed even with Professor Hale's new instrument. The beautiful corona which surrounds the ordinary Sun can only be seen when there is a total eclipse of the Sun,
Fig. 74.—A total Eclipse of the Moon.
and that is a comparatively rare event in our experience. Most people have never seen a total eclipse of the Sun; possibly I am the only one in the room who has; and although I have seen several, I have had to travel many thousands of miles for the special purpose.
Many or all of you may have seen a total eclipse of the Moon, when the Earth comes between the Moon and the Sun and cuts off the Sun's light from it; the Earth is so much bigger than the Moon that it casts a shadow wide enough to envelope the Moon for an hour and more. You remember Jupiter's big shadow and how the little satellites disappeared into and remained in it for a long time
