President's Address. 
63 
researches, the propriety of a more regular attendance at our evening 
meetings, We should seriously underrate the benefits which a 
scientific or archseological society can confer, and, more than that, we 
should wholly misconceive its most important function, if we regarded it 
merely as a publishing society — as a machinery for giving to the world, 
through the agency of the press, the various communications which 
have been, by their authors, intrusted to it. If this were true, the 
purpose might be attained as efiiciently, and far more simply, by 
sending the communications to the Secretary. If this were true, then, 
a scientific society like ours would find it difficult to justify, if not its 
existence, at least the mode of its existence, with all the costly arrange- 
ments for holding its evening meetings, for enabling authors to read 
their Papers before the assembled society, instead of sending them at 
once to the press. Eut it is not true. It is in these Evening Meetings — 
in the opportunity there given to an author of reading before his brother- 
members a Paper as yet unpublished — in the discussion which will 
generally follow — in the questions which may be put to the author — in 
the suggestions which may be made by other members — it is in all 
these, and not in the mere publication of the Papers, that we are to 
look for the great value of a learned society. 
I take an example which is familiar to us all. "We should seriously 
underrate the value of the British Association, if we measured that 
value solely, or even principally, by the annual volume which it 
produces. And probably many do thus underrate it ; but, I think, 
erroneously. The true service which the British Association renders 
to science is not measured by its volume of Papers, when published, 
but by the discussion which these Papers evoke when read — by the 
concentration, for the time, of many minds upon the same point ; and 
by the suggestive thoughts — suggestive above all to the author of the 
Paper — which the varied intellects of those who criticize his work, and 
the difi'erent stand-points from which they regard it, may well be 
expected to produce. Few of us, perhaps, are aware how much we 
owe to this contact with other minds — how often it happens that a 
thought which we have afterwards brought to maturity has been, in 
germ, deposited in our minds by some casual remark made — some 
simple question put, by another person, whose mind is running in a 
somewhat difl'ereii^t groove. 
This consideration is so intimately connected with the utility of 
our Evening Meetings here, that I venture to exemplify it by an incident 
which occurred to myself. 
Some years ago I described to the Academy an instrument by 
which the plane of polarization of a polarized ray might be determined 
with considerable accuracy. The purpose with which I had devised 
the instrument was purely optical, and at the time I had no thought 
of any different application of it. But in the discussion which followed 
my Paper, Dr. Apjohn, whose thoughts naturally turned upon 
Chemistry, asked me whether my prism could be applied to the 
saccharometer. At the moment I said, no; giving, I believe, some 
