OcTOUEk 27, 1910] 



NATURE 



537 



be made of the able condensation of the complex sub- 

 ject of the culture, distribution, and relationships of 

 the \egro and Bantu tribes of Africa. 



An important feature, and one which will be widely 

 appreciated, is the large number of illustrations, 

 many of them in the form of plates. The gco- 



Contemporai y portrait figure in wood of Bope, great chief of the 

 Bu Shongo, c. 1790. Kasai District, Congo State. From the 

 British Museum " H:.mlhook 10 the Ethnographical Collections." 



t;raphical and tribal index also adds greatly to the 

 value of the book for reference purposes. 



Whilst sriving ungrudging praise to the handbook, 

 the hope must be expressed that the extension of 

 the museum buildings will afford opportunity for the 

 accommodation of the ethnographical collections 

 under conditions that will enable them to be dis- 



NO. 2139, VOL. 84] 



played in a manner more worthy of their importance. 

 The provision of a section of technology, for example, 

 would not only be an extremely popular addition, but 

 would immensely increase the educational value of 

 the collections. It seems doubtful, however, whether 

 those who intermittently rule over us have vet been 

 convinced that museums are educational institutions. 

 It is certain that they have not appreciated the im- 

 portance of the study of man, working-man excepted. 



H. S. H. 



SIGHT TESTS IN THE MERCANTILE MARINE. 

 T^ HE Board of Trade has issued an important 

 -•■ report (Cd. 5256) on the sight tests used in the 

 mercantile marine during the yesr 1909. Out of 

 6084 candidates, 56 failed in form vision, and were not 

 re-examined; while out of the remaining 0028 there 

 were 86 failures in colour-vision, of whom 31 appealed 

 and were re-examined, with the result that 15 were 

 passed and 16 were finally rejected. The total abso- 

 lute rejections were, therefore, 71 in 6084, or i"49 

 per cent. During the first ten months of the year, 

 colour vision was tested by the three skeins of wool 

 originally recommended for the purpose bv Holm- 

 gren ; but during November and December t« o other 

 skeins, a purple and a yellow, were added. With 

 these the rejections were in somewhat larger propor- 

 tion (rSi per cent, against i"i7) than when onlv three 

 skeins were used; but the total number of candidates 

 examined by the new method (882) was- hardlv suffi- 

 cient to afford any basis for a conclusion. 



In the case of the fifteen men who, having origin- 

 ally been rejected as colour-blind, were re-examined 

 and accepted on appeal, the report gives no informa- 

 tion on the very important point of the precise 

 methods employed in testing them, or on the precise 

 "matches " made by them, either at the first e.x- 

 amination or at the subsequent one. In the case of 

 those who were finally rejected, we are told what 

 they did. " A.B.," for example, selected " sage-grey, 

 fawn, and greenish-yellow " as matches for the green 

 skein, "greenish-blue" as a match for the pink skein, 

 " blue and carmine," as a match for the red skein, 

 and so on, until he is finally dismissed as " com- 

 pletely green-blind." But of a man who, having 

 been rejected, "appealed and passed," we are not 

 told anything but that he had previously " failed in 

 the colour-vision tests," and we have no' information 

 as to how the alleged " failure " w^as redeemed. 



There can be no question that, in every case in 

 which an original rejection has been overruled, very 

 clear evidence of error on the part of the first examiner, 

 and of special care on the part of the second one, 

 should be forthcoming. VVe- believe that failure to 

 reach correct conclusions by means of Holmgren's 

 three skeins would be due, probably in all cases, to 

 neglect of Holmgren's very precise instructions as to 

 the manner in which they should be used; and, if it 

 were found that the original conclusions of any ex- 

 aminer were often overruled on appeal, an urgent 

 necessity for reconsidering his fitness would arise. It 

 is manifest that no original rejection should be set 

 aside except upon the clearest and most satisfactory 

 evidence ; because, however much we mav sympathise 

 with instances of hardship, if such there be, or with 

 worthy men deprived of a calling, it must be remem- 

 bered that the difference between red and green is to 

 the. normal-sighted so complete and absolute that they 

 can scarcely understand even the possibility of con- 

 founding them. A case in which the difference is 

 less than this, a case in which there is any question, 

 any possibility, of confusion between the two colours 

 in any conditions of weather or of illumination, is 



