54 
but the parallax of Henderson gives only 24, which approaches 
very closely to that given by the spectrum. 
I now proceed to select a few illustrations from the Belfast 
Address of Professor Tyndall, but, with the exception of the 
first, of a kind to show how hypotheses are built upon insuffi- 
cient evidence, and consequently are not scientific. I begin 
with his opening sentence : “ An impulse inherent in primeval 
man turned his thoughts and questionings betimes towards the 
sources of natural phenomena. The same impulse, inherited 
and intensified, is the spur of scientific action to-day. Deter- 
mined by it, by a process of abstraction from experience, we 
form physical theories which lie beyond the pale of experience, 
but which satisfy the desire of the mind to see every natural 
occurrence resting upon a cause/’ 
Pie first speaks of a scientific impulse , of a determination in 
a certain direction. Is there any evidence of this impulse V Yes. 
abundant evidence in our own conciousness. We know that 
when we see a change we cannot help believing in a cause for the 
change, and when more actively intelligent, we are impelled to 
search for that cause. From this we infer that if such search 
be an inherent impulse, it will often, if not always, act without 
reference to expediency or profit. 'Phis deduction is fully 
verified in the fact that numbers are enthusiasts in this search 
who never hope to receive any equivalent in the way of pru- 
dential recompense. But we have also the affirmation that the 
impulse is inherent in primeval man ; that is, not derived from 
inheritance, or obtained by experience. The evidence for this 
is that there is no trace whatever in our supposed ancestors, the 
monkeys, of turning their thoughts towards the sources of 
natural phenomena; being found in the first men, it could 
not be inherited, so must be inherent. So far I think the Pro- 
fessor is thoroughly scientific, though his first proposition 
directly negatives nearly the entire remainder of his address. 
But I regret that I cannot long coincide with him, for in his 
second sentence he speaks of this impulse as being inherited 
by us. This is surely a flaw, for if it was not inherited by the 
first man, what reason have we for inferring that it was 
inherited by any of his descendants? If it were inherent in 
him, why should we not say that it is inherent in ourselves ? 
We now proceed to the propositions of Democritus, which are, 
all but one, accepted by Tyndall in these words : “ The first 
live propositions are a fair general statement of the atomic 
philosophy as now held. One statement in that philosophy is 
that ‘ nothing that exists can be destroyed/ ” The only evidence 
for this being, that however we may change the form of any 
