1921 .] 
Farr.—Relativity. 
247 
out to decide, and on which the fate of this great generalization partly 
hung. It is only right to say that there is still some doubt about the 
result. The best photographs confirmed Einstein’s prediction ; the others, 
distinctly the worse ones, taken from another observing-spot, gave just 
about half the value—confirming, that is to say, the older ideas. Thus 
the evidence of the best photographs is in one direction, that of the much 
worse ones in the other ; and, while one can say that there was consider¬ 
ably preponderating evidence in Einstein’s favour, yet one must also say 
that it was not all that way. For further and more conclusive evidence 
we must await observations which will be made during future suitable 
eclipses—for an eclipse to be suitable it is necessary that when the event 
takes place the sun should be in a region rich in stars, and this is not 
always the case. And that is the present position with regard to check 2. 
Check 3 is, so far, against the theory enunciated by Einstein. If his 
views are correct, it should happen that a particle vibrating in an intense 
gravitational field should do so more slowly than when vibrating in a 
gravitational field less intense. This implies that the characteristic 
vibrations of the same element (say, hydrogen) as viewed when the light 
comes from a hydrogen atom vibrating on the sun would be less rapid 
than that of the same element vibrating on the earth, and such an effect 
might, if it existed, be discovered. Up till January of this year no such 
effect had been observed, but in that month an extract from a letter from 
Professor Einstein announced that the reasons of the negative results had 
been discovered by two physicists in Bonn University; but I have seen 
no later information. If, however, the effect is discovered, it is very 
likely that the honour will fall to Bonn, as the spectroscopes there are 
amongst the very best in the world. 
Thus, while we cannot by any means say that the theory of relativity 
is proved, or that Einstein’s gravitation theory, which rests upon it, is esta¬ 
blished, yet the weight of such evidence as we have been able to accumu¬ 
late is in favour of them both. Should future investigation show that these 
great generalizations rest upon solid foundations, and are a step nearer to 
that gradual attainment of truth to which I have already referred, it will 
still further increase the conviction which the slow unfolding of nature’s 
secrets have forced upon the minds of thoughtful men. These recent ideas 
when one first comes upon them leave one in a somewhat dazed^condition. 
The whole structure of what we have hitherto thought to be reality seems 
to crumble away into a hazy nebulosity of dreaminess and doubt, and we 
feel inclined to wonder whether our own existence is in very truth a fact. 
But this state of mind will slowly pass away. Mankind is gradually learn¬ 
ing b}r slow and patient experiment and observation, guided by nature’s 
greatest gift to him—his reasoning faculty—that the universe of universes 
is not so simple in its structure as it at first sight appears to be. With the 
aid of the many new senses which experiment and research have been able 
to add to his primitive five he is gradually getting an insight into another, 
a deeper, and in truth a more real world than the world of appearance with 
which we are all familiar. So far they are only glimpses, and as we get them 
we must assure ourselves by every means in our power that they are not 
hallucinations and dreams. Having done so, we can take the next small 
step with confidence. But in the light of the greater knowledge which we 
possess over those of more ancient times, we may perhaps be permitted to 
alter Milton’s words slightly and say, instead, These are Thy wondrous 
works, Parent of good, Thyself how glorious then ! ” 
