18 ' PRESIDENTIAL ADDRESS. 
temperature of the surface and of the interior of the earth 
were necessarily well adapted for the development of life, 
still, the proportions between land and water might have 
been unfavourable; or if this also was suitable, there 
might not have been a due proportion of the various ele- . 
mentary substances to allow the continuous existence of life. 
For these different factors are in no way related. 
It may be urged that, among an almost infinity of worlds, 
we might expect to find an almost infinite number of dif- 
ferent combinations, and it so happens that the earth con- 
tains exactly that combination necessary for organic deve op- 
ment. But the objection is not a valid one, because eacn 
system of sun and planets in the Universe h3s, no doubt. 
been developed under identical physical laws, and from 
identical substances. They are, more or less, repetitions of 
each other, so that the nun_ber of systems makes no differ- 
ence, and the earth can only be contrasted with the other 
planets belonging to our Solar System. Now, have the 
other planets a similar composition to the earth? As they 
shine with light reflected from the sun, the spectroscope does 
not give us any information on this point, and we can only 
speculate. As the composition of the sun differs consider- 
ably from that of the earth, we have no reason for supposing 
hat all the planets are similar. On the contrary, if the 
meteoric hypothesis be true, and if the meteorites which now 
fall on the earth are samples of the meteoritic cloud out of 
which the Solar System was formed, the planets cannot have 
identical compositions, because the meteorites differ con- 
siderably from each other, and no two aggregations of them 
would give rise to similar bodies. If, on the other hand, 
‘the present meteorites are not surviving examples of the 
original cloud, but have been drawn into the Solar System 
after it was formed, then it is impossible to form any opinion 
on the chemical composition of the planets. 
If, however, we were to suppose, for the moment, that the 
chemical composition is uniform throughout the Solar . 
System, it would not help us much, for the proportions 
which would be suitable for the earth would not be suitable 
for a planet which was either larger or smaller than the 
earth. This is evident from the fact that the ratio of the 
surface to the volume varies with the size of the planet. In- 
deed, from physical considerations alone, we may feel jsure 
that, at the present time, living protoplasm could not exist 
in any part of the Solar System, except on the surface of the 
earth. 
We have, therefore, in the composition, size, and position 
of the earth, overwhelming evidence of design. And, as we 
ee +s et Se” Ser 
