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TEANSACTIONS OF THE SECTIONS. 



Section A.— MATHEMATICAL AND PHYSICAL SCIENCE. 

 President of the Section— Captain W. de \V. Abney, C.B.,E.E., F.E.S.,F.R.A.S. 



THURSDAY, SEPTEMBER 12. 



The President delivered the following Address : — 



The occupant of this chair has a difficult task to perform, should he attempt to 

 address himself to all the various subjects with which this Section is supposed to 

 deal. I find that it has very often been the custom tliat some one branch of science 

 should be touched upon by the President, and I shall, as far as in me lies, follow 

 this procedure. 



This year is the jubilee of the practical introduction of photography by Daguerre 

 and Fox Talbot, and I have thought I might venture to take up your time with 

 a few remarks on the effect of light on matter. I am not going into the history 

 of photography, nor to record the rivalries that have existed in regard to the 

 various discoveries that have been made in it. A brand-new historv of photo- 

 graphy, I dare say, would be interesting, but I am not the person to write one ; 

 and I would refer those who desire information as to facts and dates to histories 

 which already exist. In foreign histories perhaps we Euglish suffer from spealdng 

 and writing in a language which is not understanded of the foreign people ; and 

 the credit of several discoveries is sometimes allotted to mitionalities who have no 

 claim to them. Bo that as it may, I do not propose to correct these errors or to 

 make any reclamations. I leave that to those whose leisure is greater than mine. 



I have often asserted, and I again assert, that there should be no stimulus for 

 the study of science to be compared to photography. Step by step, as it is pur.«ued, 

 there_ should be formed a desire for a knowledge of all physical science. Physics, 

 chemistry, optica, and mathematics are all required to enable it to be studied as 

 it should be studied ; and it has the great advantage that experimental work is 

 the very foundation of it, and results of some kind are always visible. I perhaps 

 am taking an optimist view of the matter, seeinijr there are at least 25,000 living 

 facts against my theory, and perhaps not 1 per cent, of them in its favour. I mean 

 that there are at least 25,000 persons who take photographs, and scarcelv 1 per 

 cent, who know or care anything of the ' why or wherefore ' of the processes, so 

 far as theory is concerned. If we call photography an applied science, it certainly 

 Las a larger number who practise it, and probably "fewer theorists, than any other. 



He would be a very hardy man who would claim for Niepce, Daguerre, or Fox 

 Talbot the discovery of photograpliic action on matter. The knowledge that -such 

 an action existed is probably a.s old aa the fair-skinned races of mankind, who must 

 have recognised the fact that light, and particularly sunlight, had a tanning action 

 on the epidermis, and the women then, as now, no doubt took their precautions 

 against it. As to what change the body acted upon by light underwent it need 

 scarcely be said that nothing was known, and perhaps the first scientific experi- 



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