52 



NATURE 



[May 19, 1887 



possesses an independent grasp of the subject. The only 

 notable instance of lack of insight is in the section on 

 continuants, where two pages (pp. 179, 180) are uninten- 

 tionally devoted to proving the theorem — 



mA _ A 



mB ~ B' 

 this very theorem itself being employed in the proof. Mr. 

 Hanus will doubtless yet come to see that the book in 

 which this originally appeared requires to be perused in a 

 spirit of scepticism rather than of faith. We may note 

 also that the identity (5) on p. 37 is exactly the same as 

 (3) on the preceding page, that the footnote on p. 196 is 

 misleading, and that the investigations referred to on 

 p. 199 might with advantage have been further drawn 

 upon. These latter, however, are small points which can 

 be attended to in the second edition. The book, on the 

 whole, is trustworthy, and well adapted for College use. 

 On this account, and as being the first American text-book 

 on the subject, it deserves a cordial welcome both in 

 America and in Britain. Thomas Muir. 



OUR BOOK SHELF. 



The A B C of Modern Photography. 22nd Edition. 

 (London : The London Stereoscopic and Photographic 

 Company, 1887.) 



Although this is called a new edition, it is really a new 

 book, having been reconstructed and much new matter 

 added. Those who are about to begin photography cannot 

 do better than study and carry out the instructions which 

 are here clearly stated. The book is divided into two 

 parts. 



In Part L the beginner is taken through the whole pro- 

 cess — exposing, developing, printing, &c. — and this is 

 followed by tables of weights and measures. 



Part II. contains good accounts of all the advanced 

 parts of the art, such as re-touching, portraiture, &c., 

 together with chapters on photo-micrography, instant- 

 aneous photography. One of the latest developments 

 of photography is shown in the "detective book 

 camera," which has the appearance of an octavo book 

 of a thickness corresponding to about 200 pages. The 

 new method of taking negatives on paper is fully described. 

 Lastly, under the headings of " New Apparatus and 

 Processes," Rayment's patent tripod top is mentioned, 

 which allows the camera to be pointed in any direction, 

 and also the patent photographic Gladstone bag, which 

 is fitted up so as to contain a complete photographic 

 outfit. We must not omit to say that the book is fully 

 illustrated, the frontispiece being a photo-mezzotype taken 

 by a pupil of the Stereoscopic Company. 



JVewcastle-upon-Tyne Public Libraries. Supplementary 

 Catalogue of Books added to the Lending Department. 

 (London : G. Norman and Son, 1887.) 



In this supplement the compiler has given nearly as 

 much space to 10,000 volumes as was occupied by twice 

 that number in the catalogue pubUshed in 1880 (see 

 Nature, vol. xxiii. p. 262). Most of the works have been 

 published smce 1880, but some earlier books have also 

 been added. The rapid accumulation of knowledge makes 

 It extremely difficult to provide adequate references to the 

 subjects of pamphlets and of articles in treatises and 

 serial publications. The compiler has, however, recoo-- 

 nized the importance of this part of his work, and the 

 results of the labour he has devoted to it will be of real 

 service to students who may have occasion to consult the 

 supplementary catalogue. 



LETTERS TO THE EDITOR. 



[ The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he under- 

 take to return, or to correspond with the writers oj, 

 rejected manuscripts. Mo notice is taken of anonymous 

 com m unications. 



[The Editor urgently requests correspondents to keep their 

 letters as short as possible. The pressure on his spcue 

 is so great that it is impossible otherwise to insure the 

 appearance even of communications containing interesting 

 and novel facts. '\ 



Thought without Words. 



I DO not see that Prof. Max Miiller's theory of the inseparability 

 of thought from language, whether true or erroneous, has any 

 important bearing on the origin of man, whether by evolution or 

 otherwise. It is a question at all events to be studied by itself, 

 and to be tested by such experiments as we can make by intro- 

 spection, or by such facts as can be ascertained by outward 

 observation. 



My own opinion is strongly in favour of the conclusion urged 

 by Mr. F. Gallon. It seems to me quite certain that we can 

 and do constantly think of things without thinking of any sound, 

 or word, as designating them. Language seems to me to be 

 necessary to the progress of thought, but not at all necessary to 

 the mere act of thinking. It is a product of thought ; an ex- 

 pression of it ; a vehicle for the communication of it ; a 

 channel for the conveyance of it ; and an embodiment 

 which is essential to its growth and continuity. But it 

 seems to me to be altogether erroneous to represent it as any 

 inseparable part of cogitation. Monkeys and dogs are without 

 true thought not because they are speechless ; but they are 

 speechless because they have no abstract ideas, and no true 

 reasoning powers. In parrots the power of mere articulation 

 exists sometimes in wonderful perfection. But parrots are no 

 cleverer than many other birds which have no such power. 



Man's vocal organs are correlated with his brain. Both are 

 equally mysterious because they are co-operative, and yet separ- 

 able, parts of one "plan." Argylx.. 



Argyll Lodge, Kensington, May 12. 



Having much of the same experience as Mr. Gallon, I never- 

 theless prefer dealing with a larger group of facts. I have often 

 referred to the mutes of the seraglio at Constantinople, who 

 cannot be charged with thinking in words. They have their own 

 sign conversation among themselves, and which has no necessary 

 reference to words. Even the names of individuals are suppressed 

 among themselves, though they sometimes use lip reading to an 

 outsider to make him understand a name. Anyone having a 

 knowledge of sign language is aware that it is independent of 

 words. The tenses of verbs, &c., are supplied by gestures. 



The mutes are not deficient in intelligence. They take a great 

 interest in politics, and have the earliest news. It is true this is 

 obtained by hearing, though they are supposed to be deaf-mutes, 

 but among themselves everything is transmitted by signs. 



Hyde Clarke. 



32 St. George's Square, S.W., May 12. 



I THINK that all who are engaged in mechanical work and 

 planning will fully indorse what Mr. Francis Galton says as to 

 thought being unaccompanied by words in the mental pro- 

 cesses gone through. Having been all my life since school-days 

 engaged in the practice of architecture and civil engineering, I 

 can assure Prof. Max Midler that designing and invention are 

 done entirely by mental pictures. It is, I find, the same with 

 original geological thought — words are only an incumbrance. 

 For the conveyance and accumulation of knowledge some sort 

 of symbols are required, but it appears to me that spoken lan- 

 guage or written words are not absolutely necessary, as other 

 means of representing ideas could be contrived. In fact, words 

 are in many cases so cumbersome that other methods have been 

 devised for imparting knowledge. In mechanics the graphic 

 method, for instance. .^ T. Mellard Reade. 



On reading Mr. Gallon's letter, I cannot help asking how 

 Prof Max Miiller would account for early processes of thought 

 in a deaf-mute : does he deny them ? S. F. M. Q. 



