332 



NATURE 



{Feb. 6, 1879 



pyroxyline, which, during decomposition, liberated nitrous acid; 

 and that this acid would destroy (before development) a photo- 

 graphic image on collodion, made from such pyroxyline. — Capt, 

 Abney then discovered that as an excess of alkaline bromide 

 would not diminish sensitiveness, or rather not prevent an image 

 being formed, consequently, if a nitrite of some alkali, in con- 

 junction with an excess of bromide, were added, the formation 

 of any acid would be prevented, so that by the application of an 

 alkaline carbonate to the film, all nitrous acid liberated from 

 pyroxyline is absorbed to form an alkaline nitrite, and the de- 

 struction of the photographic image avoided. 



Cambridge 

 Philosophical Society, December 2, 1878. — Prof. Liveing, 

 president, in the chair. — Dr. G. W. Royston-Pigott made a com- 

 munication to the Society on a new method of determining the 

 limits of microscopic vision. The author referred to his method 

 of forming miniatures by reversing an object-glass which has 

 been described in the Philosophical Transactions, and showed 

 how he had applied it to determine the limit of smallness of 

 objects that could be detected by the microscope. The process 

 employed was to form a miniature of an object such as a spider- 

 line, and then examine the miniature with the microscope. In 

 this manner Dr. Royston-Pigott had found that objects even as 

 small as the millionth of an inch in diameter could be seen, 

 contrary to the generally received view of opticians that it was 

 useless to attempt to perfect the microscope further, as it could 

 not show objects smaller than the hundred-thousandth of an 

 inch in diameter. Dr. Jurin found that with the naked eye he 

 could discover a pin fixed in a window forty feet away from 

 him, subtending an angle of two or three seconds, but if he 

 placed two pins together he could not distinguish them as 

 separated except they were so far apart as to make an angle of 

 forty seconds. Thus a bright interval could not be discovered 

 unless it were ten or fifteen times larger than the objects forming 

 it ; but Dr. Royston-Pigott found that the excellence of modern 

 objectives was such as to enable the eye to discern an interval 

 only four times larger than the diameter of the web miniature, 

 reckoned at one millionth of an inch. The microscopes and 

 apparatus employed to produce the miniature were exhibited to 

 the Society, and the precautions to be taken in the use of the 

 method were explained. — Mr. W. M. Hicks communicated some 

 results of an investigation on the motion' of two cylinders 

 surrounded by fluid. 



Paris 

 Academy of Sciences, January 27. — M. Daubree in the | 

 chair. — The following papers were read : — Third reply to M. 

 Berthelot, by M. Pasteur. — On the development of the pertur- 

 bative function where, the excentricities being small, the mutual 

 inclination of the orbits is considerable, by M. Tisserand. — On 

 a formula giving approximately the moment of torsion, by M. 

 de Saint-Venant. — Researches on the relations of spectrum 

 analysis to the spectrum of the sun, by Mr. J. Norman Lockyer. 

 — On the electric clutch-gear on board ships, by MM. Treve 

 and Achard. An arrangement for managing marine engines or 

 helms at a distance electrically. — On the composition of banana 

 and attempts at utilisation of this fruit, by MM. Marcano and 

 Muntz. The banana keeps the ground moist round it, and this 

 property is utilised in Venezuela to help the coffee-plant in dry 

 weather. But only a little of the banana's fruit is there used, 

 and the authors call attention to the flour and the alcohol ob- 

 tainable from it, recommending exportation. The flour is a 

 food essentially feculent. — On the application of his atomic 

 theory to various minerals, by M. Gaudin. — On the diameters of 

 the sun and of Mercury, deduced from the transit of May, 1878, 

 by M. Cruls (Rio de Janeiro). The solar semi-diameter is found 

 15' S9"'982, agreeing nearly with Leverrier's 16' o""o (deduced 

 from previous transits). The value for the planets' diameter, got from 

 observations of ingress, was io"*78, by another method io"74. 

 — Hydro-electricity and hydro-magnetism ; analytical results, 

 by M. Bjerknes. — On a development in series, by M. Picard. — 

 Displacement of spectral lines due to motion of rotation of the 

 sun, by M. Thollon. His experiments on this with his new 

 prism convince him that with a suitable arrangement the dis- 

 placement maybe produced in an incontestable manner. The 

 telluric lines did not show any change, and some of them, near 

 those of nickel, enabled one to see very distinctly how the latter 

 were displaced. — On the radiation of incandescent platina, by 

 M. Violle. He measured this from 900 to i,77S degrees. The 

 intensity of a given radiation does not increase indefinitely with 

 the temperature, but passes through a maximum and then 



decreases to a point, where it becomes insensible. The luminous 



heat of fused platinum transmitted through alum is — of the 



total heat transmitted through rock-salt.— On the illumination of 

 Imes of molecular pressure, and on the trajectory of molecules, 

 by Mr. W. Crookes. M. Du Moncel said the dark space is 

 not only manifested in vacuo ; it is distinctly seen round the 

 negative electrode, on sending an induction spark between two 

 plates of glass, and examining it with a microscope. (A figure 

 is given.)— On electrodynamic phenomena, and especially on 

 induction, by M. de Meaux. In a closed circuit, you do not 

 change the intensity of the current produced by induction 

 of an indefinite cylindrical conductor on another of the 

 same form, by surrounding one or other, or even both, of these 

 conductors with a concentric metallic envelope, communicating 

 with the ground throughout its length.— On a new Bell telephone 

 speaking with loud voice, by M. Gower. The two magnet poles 

 are placed opposite each other ; the diaphragm is thick, large, 

 and tense ; the inclosing case is metallic and sonorous, and" a 

 speaking trumpet is added.— On the amalgams of chromium, 

 manganese, iron, cobalt, and nickel, and on a new process of 

 preparation of metallic chromium, by M. Moissan. This method 

 is, stirring a concentrated solution of protochloride of chromium 

 in water with pasty sodium-amalgam ; the amalgam of chromium 

 obtained is then heated to 350" in a current of hydrogen. Amal- 

 gams of the other metals named may be had similarly. — On a ' 

 preparation of methylformic ether and of pure methylic alcohol, ' 

 by MM. Bardy and Bordet.— On the principles which give 



Sarracenia purpurea its therapeutic properties, by M. Hetet. 



On the termination of the visceral arterioles of Arion rufus,' hy 1 

 M. Jourdain. — Researches on the action of grenat, or the 

 residue of the manufacture of fuchsine, by M. Jousset de 

 Bellesme. This is used to colour wines. It may be taken 

 in large quantities without causing death ; but it is hurtful, 

 producing uroemia, &c.— On the quantity of light lost in 

 actuating the visual apparatus, and its variations under dif-l 

 ferent conditions, by M. Charpentier. A light being gradually^ 

 increased from zero, you note when the eye perceives it ;f 

 it may then be reduced considerably without the eye ceasing ' 

 to perceive it. This difference is much greater, if the eye have 

 been kept in the dark five minutes or more. But this effect of 

 rest in the dark does not apply (or very little) to chromatic 

 sensibility. The author considers the sensation of light wholly 

 independent of that of colour. — On the phosphorescence of the 

 lobster's flesh, by MM. Bancel and Husson. They consider it 

 due to a kind of fermentation. — M. Mege Mouris presented "a 

 note on the properties of marine salt ; and MM. Nasse and De- 

 charme, notes on a liquid rain which lately covered the ground 

 with a thick surface of ice. 



CONTENTS Page 



Entomology in America ; ,30 



Guthrie's Physics. By Prof . J. Clerk Maxwell, F.R. S. .' . '. \A 

 Our Book Shelf :— 



" The Journal of the Royal Agjricultural Society of England " . . 012 



Clark's " Visit to South America " , ,12 



Parsloe's " Our Railways " ....'. 31- 



Letters TO THE Editor :— * ' ' 



The Formation of Mountains and the Secular Cooling of the Earth.l , 



G. H. Darwin ^j,^ 



Storm Warnings.— A. Hutton Burgess •' • 313 ' 



The Dissociation of Sal-Ammoniac— An Experiment. — Dr. Wil- •' 



LiAM A. TiLDBN {JVUh Illustration) ^j. ; 



The Sting of the Bee.— Thomas R. R. Stebbing .....'. 314, 



Fossil Forests and Siliclfied Trunks.— Dr. Otto Kijntze . . . 314' 



Force and Energy.— J. G. H 31^ 



Electrical Phenomena. — Dr. Marshall Hall 31* 



Ear Affection. — P 315* 



Relation of Meteorites to Comets. By Prof. H. A. Newton . 315* 



A Zoological 'Laboe ATORY (H^it/i/llustraitou') 317' 



Biological Notes : — 



Caspian Sea Algae , jig' 



Natural History of the Caucasus 319 



On Sprouting in Isoetes 319 



The Brittle Stars of the Challenger 319 



Spines of Echini 319 



The Food of Fishes 319 



The Electricity of the Torpedo, II. By Dr. Francois Franck 



(With Illustrations) 3J0! 



Science in Lancashire and Cheshire , 322 



A Real Telegraph {JVith Illustration) 333 



Geographical Notes 333 



Engineering Research 324 



Notes 325 



Forest Geography. By Prof. As A Gray {With Illustratiens) . . 327 



University and Educationai, Intelligencb 330 



Scientific Serials 330 



Societies and AcademibsJ ........... ...»33o 



