1890.] President's Address. 471 



in the ' Philosophical Transactions,' the ' Proceedings,' and the 

 * Archives,' having been completed, the binding of them is now going 

 forward. 



The Royal Society has always been ready to assist the Government 

 of the day when requested so to do, by expressing its opinions or 

 offering its advice on questions involving special scientific knowledge. 

 Last year I received, as your President, a request from the President 

 of the Board of Trade that I should, in conjunction with two Fellows 

 of the Royal Society nominated by me in consultation with the 

 Council, examine a report in two parts presented by the Corporation 

 of the Trinity House to the Board of Trade, relative to Lighthouse 

 Illuminants, and express our opinion whether the conclusions of the 

 Trinity House, as set forth in their Reports, are justified by the 

 records of the experiments contained therein. Lord Rayleigh and 

 Sir William Thomson were asked, and consented, to join me as 

 referees, and our Report was some time ago sent in to the Board of 

 Trade, and is now in the hands of the public. 



Another subject in which scientific principles are blended with 

 practical application, is that of colour blindness in its relation to the 

 correct perception of coloured signals used at sea and in the railway 

 service. It is easy to understand what serious accidents might be 

 occasioned, for instance, by confusing red with green ; aud so well is 

 the liability to such confusion, arising from a not very rare abnormal 

 condition of colour perception, understood at the present day, that 

 persons who propose to engage in service at sea or on the railways 

 are now, as a matter of course, examined as to their perception of 

 colour. But, glaring as the difference between red and green appeal's 

 to persons whose vision is normal, the detection of those who are 

 liable to confound them, and who, for the most part, are quite un- 

 conscious that they see colours differently from people in general, is 

 by no means so easy as it might appear at first sight ; and there 

 appeared reason to think that sometimes the tests applied are defec- 

 tive, and let pass persons who are afflicted with this peculiarity of 

 vision, while, on the other hand, they may lead to the rejection of 

 persons whose vision is normal, perhaps, after they have engaged as 

 they hoped for life in an employment for which normal vision is 

 demanded. Mr. R. Brudenell Carter wrote a letter to us suggesting 

 that we should appoint a committee to investigate the subject of 

 colour blindness, and after discussion of this proposal I was requested 

 to write a letter to the President of the Board of Trade informing 

 him that, should the Government desire it, the Council will be pre- 

 pared to appoint a committee to consider the whole question of colour 

 blindness. A reply was received from the Board thanking us for the 

 communication, and saying that they regarded with satisfaction the 

 proposal of the Council to appoint such u committee. A committee 



