EVENING DISCOURSES. 753 
need to explain the periodicity which is so marked a feature and is partially 
responsible for the effects of diffraction. It is this consequence of the wave 
theory which was so brilliantly developed by Young and Fresnel, and which 
must form an essential part of any explanation of the radiation process. While 
we feel that we may have been hasty in neglecting altogether the form and the 
ideas of the corpuscular theory, we must somehow contrive to retain the positions 
which the wave theory has won for us. 
It is curious to reflect that Newton rejected the pulse theory for wrong 
reasons, and Huygens the corpuscular theory for reasons also mistaken. It is 
even more curious to consider how little their mistakes affected their work. 
Their theories were no more to these men than familiar and useful tools. 
Much of the heated argument in which we occasionally indulge arises from the 
failure to recognise that hypotheses are in the first instance made for personal 
use. We really have no justification for demanding that others shall adopt the 
means which we find most convenient in the modelling of our own ideas. 
MONDAY, SEPTEMBER 9. 
Modern Problems relating to the Antiquity of Man. 
By Arruur Kerru, M.D., LL.D. 
On my bookshelves there is placed a series of odd volumes containing past 
Reports of this Association which Fortune sent my way many years ago on a 
Whitechapel bookstall. Among them there is one volume I prize—that which 
contains the history of the meeting at Aberdeen in 1859. In that volume you will 
find an early phase of the subject of my discourse for this evening—the 
Antiquity of Man. Sir Charles Lyell presided over the Section of Geology; in 
his opening address he announced that ‘a work will very shortly appear by 
Mr. Charles Darwin—the result of twenty years’ observation and experiment,’ 
and that the evidence which had accumulated in recent years ‘made it probable 
that man was old enough to have co-existed at least with the Siberian Mammoth.’ 
From other,statements made in his address it is clear that Lyell was then con- 
vinced that man’s appearance on earth was infinitely older than the limits fixed 
by Biblical record. I do not suppose I have a single listener who heard that 
address in Aberdeen 53 years ago, but even those who are not yet old will 
concede that the new doctrine, even as preached by Sir Charles Lyell, was 
not likely to be acceptable to the general membership of the Geological Section 
in the year 1859. You will find an exact record of what happened at the meeting 
not in the official report of the year, but in the letters of Mr. William Pengelly, 
the explorer of Kent’s Cavern. Orthodoxy was represented at the meeting by 
the Rev. Dr. Anderson, who, in Mr. Pengelly’s words, ‘attempted to castigate 
Lyell for his opening address. There was a considerable amount of orthodoxy 
in the room, and Dr. Anderson got a very undue share of applause.’ The doctrine 
which Lyell and his companions championed in the face of public opprobrium 
in 1859 is the accepted and orthodox opinion of the vast majority of thoughtful 
people in the year 1912. 
That splendid movement of the nineteenth century, which knocked the 
shackles of tradition from the problem of man’s origin, was led by men of 
courage, conviction, and sound judgment. It was a progressive and victorious 
movement they initiated ; but in every movement of that kind there comes a time 
when those who cleared the way turn circumspect, cautious, and more critical 
than constructive. Opinion tends to become fixed and conventionalised, and 
then a new heterodoxy raises its head. That is the phase which we, who make 
a special study of the facts relating to man’s origin, seem to have reached now. 
I cannot cite a more stalwart or distinguished representative of the orthodox 
opinion of to-day than Professor Boyd Dawkins, of Manchester. In his Huxley 
Lecture of 1910 he gives very clearly his opinions on the antiquity of man—ripe 
convictions which are founded on a lifetime of active investigation and study. 
In his opinion the history of man does not extend beyond the Pleistocene period 
—the phase of the earth’s history which immediately precedes the one in which 
1912. 30 
