578 



NA TURE 



[October 13, 1904 



so as to bring them up to date. A striking instance of 

 this is afforded by the one on giraffes, which tal-ces no 

 notice of the new forms described in " Animal Life " 

 for 1903, and in the Proceedings of the Zoological 

 Society for the present year. A minor instance is the 

 statement (p. 212) that the aard-vark is represented 

 in the exhibition galleries of the Natural History 

 Museum by a specimen mounted in 1841, that speci- 

 men having been removed considerably more than a 

 year ago, and replaced by a new one. Again, on 

 p. 56, Mr. Renshaw repeats his statement that an 

 antelope skull in the Museum of the Royal College of 

 Surgeons is that of the extinct blaauwbok, whereas 

 Mr. O. Thomas has expressly stated in the Field that 

 it pertains to the roan antelope. If the author adheres 

 to his original view, he should at least have attempted 

 to refute the statement of an expert like Mr. Thomas. 



Fig. I.— a Gr4 



Natural History i'->- 



A further instance of what may be called 

 " opinionism " on the part of an amateur is afforded 

 by the case of the quagga in the Natural History 

 Museum, which Mr. Renshaw, in opposition to the 

 museum authorities, believes to be one which was 

 brought to London in 183 1. The evidence indicates, 

 on the contrary, that this specimen is without doubt 

 one received by the Zoological Society in September, 

 1858, which died, or was killed, in June, 1864, 

 and was acquired by the museum in July of the same 

 year, as is indicated by its register number (64.7.2.3). 

 Equally erroneous, unfortunately, is the statement on 

 p. iQi that the Amsterdam quagga was a Knowsley 

 Menagerie specimen, as has been pointed out in a 

 recent issue of the P.Z.S. Per contra, Mr. Renshaw 

 is to be credited with pointing out that the quagga 

 depicted in " Wood's Natural History " is one of the 

 specimens living in the " Zoo " during the 'sixties, 

 since the figure indicates an animal clearly identical 

 with those represented in the " Knowsley Menagerie," 

 and thus serves to identify the quaggas of the 'sixties 

 with those figured in older works, which have been 

 thought to be different. The reference to a statement 

 niade in 1801 as to the protective nature of the mark- 

 ings of the zebra (p. 165) is likewise a point on which 

 the author is to be congratulated. 



Reverting to errors, we may direct attention to the 

 NO. 1824, VOL. 70] 



misappropriation of the name Felis pardina (p. 19) to 

 the ocelot, of which the proper title is F. pardalis, 

 pardina being the appellation of the Spanish lynx. In 

 popular works the use of scientific names should, in 

 our opinion, be mostly avoided, but if they are used 

 they should be correct ; a transposition of names like 

 the above is every bit as bad as calling a lion a tiger ! 

 Another example of the necessity for care in the em- 

 ployment of scientific names in works of this nature 

 occurs on p. 133. In one sentence on that page \vc 

 find the name Rhinoceros antiquitatis, and later on the 

 title " woolly rhinoceros," but there is nothing to 

 indicate to the uninitiated that these denote one and 

 the same animal. 



If only the author had paid a little more attention 



to the revision of his articles he might have converted 



a very interesting volume into a really valuable record 



of the past history of several extinct and 



waning forms. R. L. 



DEVELOPMENTS OF THREE-COLOUR 

 PHOTOGRAPHIC PROCESSES.' 



II. 



HAVING obtained the three colour records 

 it remains to use them for locating the 

 colour in the production of the final print. If 

 the coloured lights are to be added, as in 

 Ives's chromoscope, then a transparency is 

 made from each colour record (which is, of 

 course, a negative), and each transparency is 

 made to furnish light of a similar colour to 

 that of which it is the record. If the colours 

 are to be superposed, as when they are printed 

 one over the other, or when coloured trans- 

 parencies are made and superposed in the 

 method of making coloured lantern-slides, 

 then a complementary colour to that of each 

 record must be used, because the absorptions 

 are added instead of the lights. In the 

 chromoscope the colours are in the form of 

 screens; they remain in the instrument, and 

 therefore are provided once for all. In the 

 other cases they are stains or inks, and an 

 amount is used up in the production of each 

 print; they are therefore used in quantity. 

 In the choice of inks and stains, the perfection 

 of colour is only a matter of degree, and those 

 colours that most nearly approach perfection may not 

 be suitable otherwise. The best colours may be (and 

 in some cases are) fugitive, so that for practical 

 purposes an inferior colour has to be used. If the 

 colour is perceptibly different from the theoretical tint, 

 then the colour records must be adjusted to make the 

 best of the available colours. When the colours are 

 superposed, as in printing on paper, at least two of 

 the three inks must be made of transparent colours, or 

 obviously tlie top colour would hide those beneath. 

 This last matter is, as Hiibl remarks, one of the most 

 important difficulties in trichromatic work, and, he 

 adds, the colour last printed will always predominate 

 over those previously applied. Hiibl, in his treatise, 

 describes how to select the inks bv means of his circular 

 spectrum colour scheme, and how to mitigate the 

 errors due to the defects of the selected colours, chiefly 

 by retouching and by setting off one defect against 

 another. The inks may be selected also by the use 



1 "The Water-Colour Drawings of J. M. W. Turner, R.A., in the 

 National Gallery." By T. A. Cook. Pp. vi + 86 and 58 plates. (London : 

 Ca>^sell and Co., Ltd., 1904.) Price 3 guineas net. 



"Three-Colour Photography." By A. F. von Hubl. Translated by 

 H. O. Klein. Pp 148. (London : A. W. Penrose, Ltd., 1504.) 



"Photography in Colours." By R. C. Bayley. and edition. Pp. 151. 

 (London : IlilTe, Ltd., 1904.) Price ij. net. 



Continued from p. 555. 



