52 



NA rURE 



{May 19, 1 88 1 



the authors not knowhig exactly in which category to 

 place them. The authors have examined 596 persons 

 (383 men and 213 women), and found among them 76 

 "positive" (that is, capable of seeing photisms), and 520 

 '■ negative" (that is, incapable of seeing photisms). This 

 proportion is about i to 7. Particulars of the examina- 

 tions of all are given. The photisms for the same sounds 

 differ much from individual to individual, but remain 

 constant for the same individual, as shown by receiving 

 identical answers to thousands of questions after intervals 

 of more than a year. The photisms are not always dis- 

 tinct or of definite forms, but are projected on to the spot 

 whence the sounds arise. Other senses produce sensa- 

 tions of colour as well as hearing ; thus there are taste 

 and smell photisms. There are also emotional photisms. 

 The authors are unable to give any explanation, but they 

 are clear that simple association does not suffice, and they 

 examine a number of suggestions made to them, showing 

 that they do not account for cases observed. They them- 

 selves think that the solution of the difficulty is to be 

 sought in the nature of nervous processes, but they do 

 not admit that " secondary sensations " are psychopatho- 

 logical. This little book is full of curious and interesting 

 details evidently connected with Francis Galton's "mental 

 images," and localisation and sometimes colouring of 

 numbers in the mind's eye. The following account of the 

 general conclusions obtained, given on the last page of 

 the book, will show what a curious page of nervous 

 physiology is here opened out. 



1. Bright photisms are excited by musically high 

 sounds, severe pain, sharply-defined sensations of taste, 

 small forms, pointed forms. Dark photisms by the 

 contrary. 



2. Musically high phonisms are excited by bright light, 

 clear definition, small forms, pointed forms. Deep 

 phonisms by the contrary. 



3. Photisms with sharply defined forms, small photisms 

 and pointed photisms, are all excited by the sensations of 

 musically high sounds. 



4. Red, yellow, and blue are common colours of 

 photisms ; violet and green are rare, blue is of medium 

 frequency. 



5. Thorough agreement of the separate assertions of 

 different individuals does not occur. 



5. Unpleasant primary sensations may excite pleasant 

 secondary sensations, and conversely. 



7. Secondary sensations are scarcely more influenced 

 by psychical circimtstances than are primary sensations ; 

 and they are inalterable. 



8. The disposition to have secondary sensations is 

 hereditary. 



9. Traces of secondary sensations are widely spread. 

 Well-developed secondary sensations couldbe established 

 to exist for one in eight persons examined. 



10. Secondary sensations are not more frequently met 

 with in psychopathically afflicted persons than in those 

 of a normal condition. 



A List of European Birds. By Henry E. Dresser. 



(London : Published by the Author, 1881.) 

 This "List of European Birds," including all the species 

 found in the Western Palsearctic region, has been very 

 carefully revised by Mr. Dresser, and appears oppor- 

 tunely on the completion of his great work on the " Birds 

 of Europe." It will be most useful as a check list for label- 

 ling, or for reference in making exchanges of birds and 

 birds' eggs. The classification is the same as that adopted 

 in the " Birds of Europe," and follows that of Prof Hux- 

 ley, which still appears to Mr. Dresser to be the best as 

 yet elaborated. The species are numbered consecutively, 

 in order to facilitate reference. A very few alterations 

 in the nomenclature have been made: 623 species are 

 enumerated, and the list is published at the low price 

 of one shilling. 



The Seals and Whales of the B?-tiish Seas. By Thomas 

 Southwell, F.Z.S. (with Illustrations). (London: Jarrold 

 and Sons, 1881.) 

 This neat little volume, though it adds little if anything to 

 our scientific knowledge of the British seals and whales, 

 will be welcome to many as telling a good deal about these 

 interesting mammals which could only be found after a pro- 

 longed search through many of our scientific periodicals. 

 It will form a pleasant addition to sea-side libraries, and, 

 telling what is known about these creatures, it may thus be 

 the means of indicating what is not known about them, and 

 so do something towards advancing knowledge. A good 

 deal of the information in this little voluine appeared 

 originally in the pages of Science Gossipy it has however 

 not only been carefully revised, but several additional 

 woodcuts have been added. It has also had the super- 

 vision of Mr. J. W. Clark and of the late E. R. Alston. 



The inore advanced student would have liked a short 

 chapter on the literature relating to our British marine 

 mammalia, which perhaps in a future edition might be 

 given, and an analytic key to the species of British 

 cetacea M'ould be a great help to those living in suitable 

 localities who would venture to take up the study of these 

 very interesting but not easily preserved creatures. 



A Scqtiel to the First Six Books of the Elements of Euclid, 

 containing an Easy Introduction to Modern Geometry, 

 ivith numerous Examples. By John Casey, LL. D., 

 F.R.S. (Dublin University Press Series, 1881.) 

 There are many geometrical results which are not 

 directly formulated or stated in Euclid's Elements, which 

 are yet constantly turning up in the solution of geometrical 

 problems, and it is very desirable to have a handy book 

 of reference, the propositions in which may be cited, so 

 obviating the necessity of a lengthy proof The " Exer- 

 cises on Euclid and in Modern Geometry" of Mr. 

 McDowell is a useful book for this purpose, as all the 

 propositions are fully worked out. Dr. Casey, in the 

 course of teaching, has frequently had to contend against 

 the defect above referred to, and had to interrupt the 

 course of the demonstration of an advanced proposition 

 by turning on one side to prove some well-known result, 

 because he could not cite Euclid as an authority for it. 

 This handy Uttlebook, which appears to us quite up to the 

 level of the author's reputation as a geometer, is intended 

 to meet this felt want, and paves the way to a deeper 

 study of the modern geometry contained in the exhaus- 

 tive works by Chaslcs, Townsend, Mulcaby, and many 

 Continental writers. A great number of classical pro- 

 blems are led up to, and they themselves discussed and 

 established. The size and style of the book fit it for use 

 in the higher forms of our schools, and more advanced 

 students will find it a convenient book for citation. 



Accented Four-Figure Logarithms and other Tables for 

 Arithmetical and Trigonometrical Purposes and for 

 Connecting A Ititudcs and Lunar Distances, with Formulct 

 and Examples. Arranged and accented by Louis D'A. 

 Jackson. (London : W. H. Allen, 1S81.) 

 Mr. Jackson is an experienced editor and computer of 

 logarithmic tables, having already published " Accented 

 Five-Figure Logarithms," " Pocket Logarithms and other 

 Tables," &c. Different calculations require different 

 degrees of approximations, and^the computer learns by 

 experience which kind of tables are best suited for the 

 end he has in view. In his Introduction our author care- 

 fully discusses the question, and states to what extent the 

 present tables are efficacious. His system of accentua- 

 tion appears to be a good one. Certainly it insures a 

 much closer degree of accuracy than is to be got from 

 ordinary four-figure tables. Each logarithm, on its face, 

 shows whether it is in excess or in defect of the true value 

 (obtained by taking a greater number of figures), or equal 

 thereto. The range of error seems to be reduced to a 



