April 17, 1885.] 



KNOWLEDGE ♦ 



331 



history of his life here given by Professor Gardiner. We 

 note the same catholicity of selection in the second vohimo 

 of Mr. Leslie Stephen's work that struck us in the lirst : 

 to give a single example, a really full accoint appearing of 

 the life and death of that Laird of Gilnockie who was 

 executed by James V. of Scotland ; of whom, by a .strange 

 coincidence, the writer of these lines is the ninth lineal 

 descendant. We fail, by the way, to see why Arabella 

 Stuart appears under the letter " A." 



Bacillar)/ P/ithisig of the Ltings. By Geumaix Ske. 

 Translated and edited by Will!.\m Hexky Wkddell, 

 M.II.C S , itc. (London: Kegan Paul, Trench, i^- Co. 188.5.) 

 — It used to be said that the two chief English diseases 

 were consumption and apoplexy, and although the hitter is 

 scarcely now entitled to ihis old bad pre-eminence, phthisis 

 still remains as one of the most terrible of our scourges. 

 Until within a comparatively recent period its nature was 

 but imperfectly understood, and hence its pathology remained 

 in a very rudimentary condition. Thanks, however, mainly 

 to Laennec, Villemin, Pasteur, and Koch, the virulence, 

 transmissibility, and jiarasitic origin of consumption have 

 been successively made ]>lain. In fact, Koch in 1882 

 finally determined the species of parasite which is the true 

 agent in tuberculosis. Having thus traced this fell disorder 

 to its origin and established a genuine retiology of it, it 

 may reasonably be hoped that therapeutics will keep pace 

 with our advanced knowledge, and deaths from this cause 

 be notably diminished. As a contribution towards this 

 desirable end M. See's exhaustive book leaves nothing to 

 be desired. Beginning with the life-history of microphytes 

 generally, and proceeding to the specific study of that of 

 the tubercular bacillus, our author leads us through the 

 study of tubercle, its very diverse causes, diagnosis, and 

 treatment. The translatnr and editor has done his work 

 faithfully and well. This is a book which should be on the 

 shelves of every medical pi-actitioner. 



The Trochoxded Plane. By Lawrence Hargrave. — The 

 trochoided plane " is a flat surface, the centre of which 

 moves at a uniform speed in a circle, the j)lane being kept 

 normal to the surface of a trochoidal wave, having a period 

 equal to the time occupied by the centre of the place in 

 completing one revolution." In a paper on this form of 

 surface, read by its author before the Royal Society of New 

 South Wales, last year, he attempts to explain many 

 animal movements, such as swimming, gliding, flying, itc, 

 by reference to its properties. The whole subject can only 

 be studied in the pamphlet itself, by the aid of its illustra- 

 tive diagrams. 



Special Creation and Evolution, an Exposition of the 

 Openiny Chapters of Mr. Herbert Spencer's " Principles of 

 Biology." Part III. By Constance C. W. Naden. 

 (Birmingham : Cornish Brothers.) — Whoever may need a 

 compendious introduction to the study of Mr. Herbert 

 Spencer's " Biology," given in language at once graceful, 

 thoughtful, and intelligible, should straightway purchase 

 ;Mis8 Xaden's very cheap little tract. It will repay 

 perusal. 



Tlie Liberty of Independent Historical Research. By 

 Thos. Kerslake. (London : Beeves i Turner. 188.5.) — 

 Mr. Kerslake believes that he has identified Penselwood in 

 Somersetshire with the ancient British city Caer Pensauel- 

 coit General Pitt-Rivers, the recently-appointed Inspector 

 of Ancient Monuments in Great Britain says that Mr. 

 K. hasn't. " Hence," as Artemus Ward construed Horace, 

 "these weeps." All who wish to see the arguments by 

 which Mr. Kerslake justifies his discovery, must seek 

 them in the brochure whose title heads this notice. 



JTte Advertisers' Guardian By Louis Collins. (Lon- 

 don. 1885.) — Those who enjoy the polemics of advertising 



agency may buy this volume as a companion to that of Mr. 

 Sell, which wo noticed on p. 288. Mr. Collins certainly 

 gives the purchasers of his volume amusement as well as 

 information. Several excellent facsimile reproductions of 

 scarce and valuable old engravings adorn his text. 



We have also on our table Ciel et Tcrre, Report of the 

 Mitchell Library, Ghmjow, Brndstreet's, The Journal of 

 Botany, The Journal of the Society of Arts, Shop Hours 

 Regulation, The American Naturalist, Proceedings of the 

 Academy of Natural Sciences in I'hiladelphifi, J'roccedings 

 of the Geological Society, WheeVrng, The Tricyclist, The 

 Medical Press and Circular, Tlie Sanitary Ncivs, and 

 Society. 



HAND-REGULATOR FOR THE ELECTRIC 



LIGHT EMPLOYED FOR THE PROJECTION OF 



SHADOWS. 



IN' the .lournal de Chitnic Appliqufe (says the Electrical Revietu), 

 Dr. Waltc-r foiitributes a communication relative to an 

 apparatus, by the help of which it is possible, without dilliculty, 

 to render various substances incandescent for the purpose of spec- 

 trum analysis. 



It has been usual to employ the Dubosq lamp in such cases.* 

 The introduction of the substances into the cavity at the extremity 

 of the lower carbon is not an easy operation when the arc is 

 formed ; the dazzling effect of the light is very troublesome to tho 

 experimenter, and, conseriuently, often severely trios the patience 

 of the audience. Dr. Walter has constructed the apparatus — of 

 which we give a figure — which acts solely as a hand-regulatoi'. 



so that the exhibition of the ahadowa does not practically 

 occupy any time. The disc, n, of copper forms the chief part 

 of the instrument; it is 50 mm. in diameter, and 15 mm. 

 thick. It is provided at its circumference with a number 

 of radial screwed holes, in which the carbon rods (about 8 mm. 

 in diameter) are screwed in such a way that they project about 

 50 mm. Before being inserted in their places, the carbon rods aro 

 saturated in various metallic solutions, and then dried ; one of the 

 rods is left unprepared, so that it can be used to show the ordinary 

 spectrum of carbon. The plane of tho disc, B, makes a right angle 

 with the plane of the mirror of the prujeeting apparatus, and 

 scarcely cuts off more of the light than a single carbon does. In 

 order to keep b in its proper position, the axle of B carries a disc, 

 A, the contour of which is wave-shaped. By turning the axle, the 

 spring, c, drops into one or other of the depressions, and keeps the 

 disc steady in the corresponding position. On the disc, a, the 

 symbols of the elements are engraved in an order corresponding to 

 the order in which the prepared carbon rods are arranged. The 

 disc, A, is outside tho projection apparatus, so that any required 

 element can be brought in position without difficulty. 



The opposite electrode consists either of a disc similar to the 

 disc. A, or a single carbon as sliown in the figure. The sliding 

 uprights, M and E, have attached to their lower extremities the 

 ends of spirals of copper wire ; the other ends of the latter being 

 attached to the base plates, w and v. 



* For several years past an apparatus devised by M. Boudreanx, 

 and of which the principle is analogous to that described by the 

 writer, has been used in Paris. 



