June 2, 1899.1 



SCIENCE. 



771 



suppose scientific knowletlge had sooner led 

 us to recognize the close relation of elec- 

 tricity and light. Surely the mode of di- 

 vision would be quite different. The defi- 

 nition of Zoology before and after Darwin 

 would have been different. A classification 

 which then appeared to be scientific would 

 now be recognized as inadequate. The very 

 first thing we must recognize is that our 

 scientific knowledge is imperfect and grow- 

 ing, and we must adopt a system capable of 

 easy modification as our knowledge in- 

 creases. Another point which Chevalier 

 Descamps made was that we adopt different 

 methods with regard to different sciences ; 

 in some cases the numbers are followed by 

 symbols ; in some cases the numbers are 

 separated by a hyphen, and so on. We have 

 gone into this question as scientific men, 

 and, although perfectly ready to submit the 

 result of our work to the criticism of other 

 scientific men, we do believe that the plan 

 that suits best one science will not suit an- 

 other. Take one example. Take, for in- 

 stance, Zoology. There is the question of 

 arrangement of the subject in accordance 

 with the species of animals, and the 

 question of arrangement with regard to 

 the geographical distribution. Here are 

 two ideas to which there is nothing 

 similar in physics or chemistry. It would 

 be disastrous if we attempt to force all 

 these sciences to adopt the same method. 

 If two things are essentially different, we 

 do not apply the same principles to both. 

 In the last place. Chevalier Descamps says 

 the main object of classification is to tell us 

 where to find a particular object with which 

 we are dealing. I do not much believe in 

 the average memory of scientific men being 

 able to grasp a large number of numbers. 

 I believe it is much easier to find the place 

 by using symbols, which are more distinct 

 than a large number is from a small one. 

 Significant words which are for temporary 

 use have their own meaning. You find them 



alphabetically. I do think, on the question 

 of general principle, that it is very desirable 

 that the Conference should express an 

 opinion as to whether or not thej' think the 

 symbols are to be devised in such a way as 

 to help the memory or to find the place ; 

 secondl}', whether they do or do not hold 

 the view that the plan good for one science 

 is good for all, and whether it is desirable 

 to attempt to plan a scheme in the belief 

 that it will hold good for all time." 



Dr. Bernoulli said that after hearing the 

 statements in favor of the two systems he 

 wished to add that the decimal system was 

 in actual working order in Switzerland, and 

 that its practical utility had been demon- 

 strated there. He considered it superior 

 to the system proposed by the Eoyal So- 

 ciety, although originally he had been an 

 opponent of the decimal system. 



M. Deniker replied that it was necessary 

 to consult an alphabetic index to use the 

 decimal-system catalogue. He favored a 

 methodical or subject catalogue alphabet- 

 ically arranged. 



Cyeus Abler. 



Smithsonian Institution. 



( To he Concluded. ) 



CO LOB- WEAK NESS AND COLOR-BLINDNESS. 



It is generally accepted as a well estab- 

 lished fact that the traveling public is fully 

 protected by the present tests for color-blind- 

 ness to which railway emploj^ees and pilots 

 are subjected. Yet several of the mysterious 

 accidents that have occurred during the 

 last two years might be explained on the 

 supposition of color-blindness on the part 

 of responsible lookouts. In fact, I believe 

 mj'self in position to prove that persons of 

 dangerously defective color-vision actually 

 do pass the regular tests and obtain posi- 

 tions where their defects are continual 

 dangers to public welfare. 



In the first place, I have at the present 

 time among my students one who is abso- 



