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242 handed over the finished plate and put in the new one, all without a hitch or mistake of any kind. As a mere piece of drill the performance was warmly praised by a military man present in the audience. During the long (forty-second) exposure, the party of observers duly took the opportunity of regarding the corona, according to instructions; but for the rest of the time their "eyes were in the boat." At the hundredth second the corona disappeared with the reappearing crescent of the Sun, and the lamps previously lowered were relit; the eclipse was over; but all the photographs had been secured, with several seconds to spare, an achievement which was duly appreciated by the audience.]

Now the eclipse is over, and if our photographs are not properly taken we must wait till the next eclipse; we cannot repeat this one. Fortunately we have had fine weather sometimes poor astronomers travel thousands of miles, get everything ready, and then it is cloudy or raining!—but I feel sure that when we develop our plates we shall find good pictures on them. And now what is the use of these pictures when we have them? Well, I cannot bother you with all the details of eclipse work, but I will try to give one or two illustrations of the way in which knowledge may be gained by the study of these pictures; and I will take the illustrations from my own work at eclipses, not because it is more important than that of other people, but because I know more about it.

I have been measuring the brightness of the corona at different distances from the Sun. Near the Sun it is very bright, as bright as the full Moon