204 



NA TURE 



\7an. 13, 1876 



being particularly elegant. On pp. 144, 145, in the proof of 

 theimportant proposition that the ratioof anytwo rectangles 

 R and R' is the same as that of the product of the height 

 and base of the first, to the product of the height and 

 base of the second, there are two, at any rate typographi- 

 cal, errors which would exceedingly trouble boys or the 

 ordinary run of self-taught students. Also in a numeri- 

 cal example to this proposition the writer correctly gets 



pi — 4i> iind then says the first rectangle is 4^ times 



greater than the second rectangle. On p. 148 the reason- 

 ing in theorem vi. is defective, and in the scholium 

 there is a misprint ; it is, however, not necessary to dwell 

 fully on this Book V., which is especially faulty. We 

 shall close our remarks on the text by quoting a sentence 

 on p. 171, simply remarking that we could have extended 

 our* criticism to twice or thrice the dimensions of the 

 present notice. The sentence is : " The further develop- 

 ment of the Theory of Transversals is reserved for a 

 special treatise on Modern Geometry, with a popular view 

 of the recent improvements introduced by M. Chasles." 

 May it be reserved to the Greek Calends ! say 

 we. Who and what is Mr. J. R. Morell, that 

 he should venture to act as interpreter of M. 

 Chasles' brilliant contributions to Geometry 1 Such 

 a work brought out by a competent writer would be 

 of great use. It was in 1871, that Mr. Morell pub- 

 lished '"'The Essentials of Geometry, Plane and Solid, 

 as taught in French and German Schools, with Shorter 

 Demonstrations than in Euclid," &c. After the reception 

 this little work met with one would have hoped that the 

 author would have learnt wisdom, and before he sent forth 

 another such work into the world would have submitted it 

 to one or two candid and competent geometrical friends. 

 The book might yet be made a very fair one, but as it is 

 at present we must condemn it most strongly. 



There is an appendix of 205 exercises, and we have 

 marked upwards of forty as each containing something ob- 

 jectionable in language or in geometry. We must content 

 ourselves with a selection ; — 30. Given a rectangle and a 

 point situated in the interior of a quadrilateral j it should 

 be " and a point within it " (or some such words ; it is the 

 billiard-table question which is given in many French 

 text-books). 40. A triangle and any plane figure, in 

 general tnovable in a plane, &c. 42. Which is the 

 geometrical locus, &c. 103. A question of two concentric 

 circles : in Xh.e great circle, in the little one. 116 is not 

 neatly put ; it is, '" What is the geometrical locus of the 

 centres of the circles which intersect orthogonally — that 

 is, forming a right angle — two given circles ? " 143, 193, 

 he uses in the function, where an ordinary geometer would 

 write i}i terms of. In such 'wise and ifi (for " into ") fre- 

 quently occur. Before closing our article, we must point 

 out that the work we have examined is not to be cofi- 

 fou7ided with " The Elements of Geometry in Eight 

 Books ; or, First Step in Applied Logic," by L. J. V. Gerard, 

 which forms a volume in Dr. J. D. Morell's Advanced 

 Series for Colleges and Schools. This is the work of an 

 able and judicious writer ; we must at present content 

 ourselves with merely commending it to the notice of any 

 of our readers interested in the subject. A word of praise 

 we can extend to the external aspect of " Euclid Simpli- 

 fied J " it has a neat and geometrical design on the cover. 



TISSANDIERS PHOTOGRAPHY 



A History and Handbook of Photography. Translated 

 from the French of Gaston Tissandier. Edited by 

 J. Thomson, F.R.G.S. (London : Sampson Low 

 and Co., 1876.) 



ALTHOUGH one may reasonably object to the state- 

 ment made by an eminent French savant that 

 " chemistry is a French science," there is no denying the 

 fact that photography, so far as its early history is con- 

 cerned, is eminently a French art. M. Tissandier, the 

 author of the work now before us, of course does not fail 

 to impress this fact repeatedly upon his readers by 

 speaking of photography as the " art of Daguerre," and 

 indeed throughout the book he places his own country- 

 men in positions which might in some cases be justly 

 considered as somewhat too prominent. The addition of 

 some few historical notes, however, by Mr. Thomson, the 

 editor, renders the work, on the whole, as fair a history of 

 the subject as we could wish to read. 



Of the three parts into which the book is divided the 

 first is entirely historical, commencing with a description. 

 of the camera obscura of Porta, and the discovery of 

 " Luna Cornea " by Fabricius, and then proceeding to the 

 early experiments of Prof. Charles, Wedgwood, Davy, and 

 Watt. The connection of Daguerre with the first deve- 

 lopment of photography is of course known to all. The 

 early life of Daguerre forms the subject of the second 

 chapter, and the author here relates an incident which 

 may be new to many of our readers. 



It seems that in 1825 a poorly-dressed young man 

 entered the shop of Charles Chevallier, which was at that 

 time much frequented by amateurs, and demanded the 

 price of one of the new cameras with converging meniscus 

 lenses, which were then being made for the first time. 

 The young man's manner showed that the price named 

 was far above his means, and Chevallier then inquired 

 for what purpose he required the camera. The stranger 

 declared that he had succeeded in fixing the image of the 

 camera on paper, but that the instrument he had em- 

 ployed was of rough construction, and he was anxious to 

 continue his experiments with the improved apparatus. 

 Chevallier being sceptical as to this statement, the young 

 man placed on the counter beforehim a piece of paper, 

 on which appeared a view of Paris, and on further 

 questioning gave the optician a vial of blackish fluid, 

 which he stated to be the liquid with which he operated. 

 To continue, in the author's own words : — " The unknown 

 explained to the optician how he should go to work ; then 

 he retired lamenting his hard fate, which would not 

 permit him to possess that object of his dreams, a new 

 camera ! He promised to return, but disappeared for 

 ever." It may be added that Chevallier could get no 

 result with the liquid left with him. The incident was 

 related to Daguerre, but the unknown inventor never 

 appeared again, so that his name and fate remain a 

 mystery. The succeeding chapters contain an account of 

 the life and labours of Nicephore Niepce, and a history 

 of the partnership entered into between this gentleman 

 and M. Daguerre. Niepce's process, it will be remem- 

 bered, depended upon the fact that " Bitumen of Judaea," 

 when exposed to light, becomes insoluble in oil of 

 lavender. Daguerre, continuing his researches under the 



