18 SIR ROBERT S. BALL, LL.D., F.B.S., ON 
because in it we are looking at an object that no human eye 
has ever seen. The photographic plate sees it but we do 
not. The late Professor Keeler commenced a survey of the 
heavens. He took a square degree here, and one here. He 
took, if I may use the expression, samples of the heavens 
on photographic plates. On one of those plates he 
found three new nebule; on another ten; on another 
twenty, and on another even as many as thirty-—not less 
than three on any one. If he were to photograph the whole 
heavens he would want 40,000 plates. He had only taken a 
dozen or so, and had not found fewer than three on any one, 
and ten times that number on some. If there were three 
new nebule at least on each of those 40,000 plates, that 
means 120,000 new nebule in the heavens. There is an 
astonishing fact to be added, and that is, of these more 
than one-half are spirals—hence spiral nebula assume great 
importance in the celestial economy. 
Here is the last one we shall look at. It was taken by Dr. 
Roberts, and is generally believed to be the most remarkable 
astronomical photograph ever taken. It is a picture of the 
great nebula in Andromeda. If it could have been turned 
into a better position we should have found another great 
spiral. 
These pictures show how the theory suggested by Kant 
and developed by Laplace is borne out in the most astonish- 
ing manner by these. more recent observations with 
photography. 
My lecture is at an end. I began with a statement of 
the origin, so far as we are able to discover it, of these stars 
which occé asionally and suddenly burst into view. 
[have shown how those stars arise from a collision, and 
I have tried to show how by a contraction of a nebula, 
as most of us believe, the great sun that we know in heaven 
came into being with its planets. 
The whole tendency of modern science so far as we have 
been able to understand it, has been to show that what Kant 
and Laplace and Herschel laid down is, in the main, the 
actual order of events that has taken place in nature. In 
concluding my lecture to this Institute, where it has given me 
such pleasure to appear, I cannot help saying that the more 
we study these things, the greater is the mass of difficulties, 
which seem to us insuperable if we try to unravel them 
by the light of science alone. It is true, we believe—I 
myself certainly do—that our solar system has originated 
