164 



NATURE 



{Dec. 19, 1878 



observed in different parts of the same tube are probably 

 due to the existence of more than one gas in the tube. 

 Tubes of nitrogen which did not show the lines of hydrogen at 

 all when sparks from an induction coil without a Leyden jar 

 were passed through them, gave strong hydrogen lines when a 

 large jar was interposed, A bulb tube with magnesium wires 

 filled with hydrogen at low pressure gave in one half scarcely any 

 spectrum but the F-line of hydrogen, while the other half gare 

 the spectrum of acetylene. They generally found hydrogen 

 lines and flashes of sodium (no doubt from the glass) in tubes 

 very much exhausted ; and they conclude that impurities enter 

 such tubes from sources hitherto unsuspected. Tubes filled with 

 oxygen obtained from silver iodate have been found to give the 

 spectrum of iodine, pointing to the conclusion that chemical 

 reactions occur at very low pressures \\ hich are not produced 

 under other circumstances. Generally the authors conclude that 

 the spectrum of a gas in a rarefied state affords the most delicate 

 test of its purity, and that it is to the chemical problem of 

 obtaining pure gases that attention needs to be specially 

 directed. 



Paris 



Academy of Sciences, December 9. — M. Fizeau in the 

 chair. — The following papers were read : — New method for de- 

 termining the flexion of telescopes, by M. Loewy, The prin- 

 ciple is to produce in the field, besides the images of the eye- 

 piece and objective (whose position may vary), a third image 

 emanating from the axis of rotation, which, completely indepen- 

 dent of the flexion of the tubes, undergoes only a slight displace- 

 ment due to the auxiliary lens. This image serves as a means of 

 estimating the relative displacement of the two others. (A con- 

 cavo-convex lens is placed in the axis of the central cube, and on 

 its axis of rotation.) — Examples of calculation of the torsion of 

 prisms with mixtilinear base, by M. de Saint-Venant. — On the 

 binary form of the seventh order, by Prof. Sylvester. — Study on 

 ordinaiy and compound steam engines, steam jackets, and super- 

 heating, according to experimental thermodynamics, (extract), by 

 M. Ledieu. Some observations are here made on neutral spaces 

 and their influence, the restriction of these having been one 

 direction of recent improvement. — On the works of the Saint 

 Gothard tunnel, by M. Colladon. After recounting obstacles which 

 have retarded the work — among others, greatly increased and vio- 

 lent infiltration, and the swelling of a plastic mass of decomposed 

 felspar and gypsum on contact with moist air, exerting tre- 

 mendous pressure on supports — he gives information about the 

 air compressing and ventilating apparatus and the boring ma- 

 chines. It is expected that about eight years will suffice for the 

 completion of the work. The difference between the fii-st esti- 

 mated and actual expense will, it is thought, be nearly 100 

 million francs. — On a series of soundings undertaken by M. 

 Roudaire in view of the formation of the African interior sea, 

 by M. De Lesseps. These soundings will cover about 5°° 

 leagues, and will occupy M. Roudaire about six months, after 

 which it will be possible to estimate fairly the expense of the 

 project. M. De Lesseps describes what he saw of that region. 

 — Report on a memoir of Prof. Lawrence Smith on the native 

 iron of Greenland and the dolerite it contains. The reporters 

 recommend insertion of this interesting memoir in the Recttcil 

 des Savants etrangers. — Diseases of plants caused by Pero- 

 nospora ; attempted treatment ; application to the lettuce- 

 disease, P. Cangliiformis, Berk. Memoir by M. Cornu. — M. 

 Werdermann replied to M. Reynier's reclamation of pri- 

 ority with regard to the electric lamp. He maintains that 

 his (W.'s) lamp depends not on the effect of incan- 

 descence of a heated carbon, but on an extremely small 

 voltaic arc ; the incandescence of a small part of the 

 electrode is merely an inevitable consequence. — On an auto- 

 matic regulator of ciurents, by M. Hospitalier. This consists 

 of a one-layer resistance bobbin, having a portion of its wire laid 

 bare, and in contact with a slightly convex distributor connected 

 with an armature before an electro-magnet which is affected by 

 the current to be regiilated. — On a small telephonic apparatus, 

 by M. Boudet de Paris (sealed packet opened). This refers to 

 a telephone in the form of a watch, which, with a microphone, 

 gives speech well. M. du Moncel referred to a very advanta- 

 geous arrangement of a speaking microphone (by M. Boudet 

 de Paris), which he would shortly describe. — On the reduc- 

 tion, in continuous fractions, of a pretty extensive class of 

 functions, by M. Laguerre. — On a point in the history of mathe- 

 matics, by M. Desbovas. — Theorems on prime numbers, by M. 

 Proth. — On a remarkable specimen of siliciiu-et of iron, by Prof. 



Lawrence Smith. This piece is remarkably rich in silicium 

 (about 15 per cent.), and is evidently the product of a blast 

 furnace. There are no such furnaces ^\■here it was found, 

 but there are some a few miles away, and about 100 

 miles from the spot was one which supplied iron having 

 8 per cent, silicium, and gave up working because of want of 

 demand for such iron. Prof. Smith thinks the piece may have 

 been (exceptionally) produced there. M. Daubree said industry 

 has never been known to produce an alloy of iron with nearly so 

 much silicium. The highest proportion at the Exhibition was 

 10 per cent. — On a new acid obtained from camphor, by M. 

 Haller.— On the formation of hexamethylbenzine by the decom- 

 position of acetone, by Mr. Greene. — On normal ethyloxybutyric 

 acid and its derivatives, by M. Duvillier.— On the presence of 

 ytterbine in the sipylite of Amherst, by ]\I. Delafontaine. — 

 Existence of baryta and strontian in all rocks constituting 

 primordial strata ; metalliferous veins with gangue of baryta, 

 by M. Dieulafait. He infers from the facts that baryta and 

 strontian have the same origin, viz., the primordial rocks; hence the 

 metalliferous ores (manganese, lead, zinc, &c.), for which baryta 

 serves as gangue, has also this origin.— On the dangers in use of 

 borax for preservation of meat and the reasons v hy some sub- 

 stances cause m.eat to lose its nutritive properties, by ]\I. 

 Le Bon. He prescribes, in principle, the use of chemical 

 substances, even the apparently inoffensive salt, for preservation 

 of meat. The most nutritive part of meat is the juice, and this, 

 when the meat is put in saline solution or covered with a salt in 

 powder, makes rapid exchange of its nutritive principles through 

 endosmose. He hints at a new mode of preservation, however, 

 other than cold. — On an artificial pyroxene (diopside), by M. 

 Gruner. — Influence of atmospheric electricity on fructificatien of 

 plants, by M. Grandeau. It greatly stimulates the phenomenon. 

 — On a disease of the coffee-tree observed in Brazil, by M. 

 Jobert. — On the diffusion of heat by leaves, by M. Maguenne. — 

 On the power of absorption of water by wood, by M. Maumene. 

 The property varies (for different woods) between 9*37 and 

 174-88 per cent, of the absolutely dry wood; the latter figure 

 was obtained with chestnut. — On a scientific balloon ascent of 

 October 31, by M. Tridon. 



CONTENTS 



Paradoxical Philosophy. By Prof. J. Clerk Maxwell, F.R.S. . 141 



Science Class-Books 143 



Our Book Shelk: — 



" Studies from the Physiological Laboratory in the University o£ 



Cambridge" 1^5 



"The American Quarterly Microscopical Journal, containing the 



Transactions of the New York Microscopical Society" . . . 145 

 Letters to the Editor : — 



Locusts and Sun-Spots. — E. D. Archibald 145 



The Range of the Mammoth.— Prof. W. Boyd Dawkins, F.R.S. 146 



Fossil Floras of the Arctic Regions. — J. J. Wild 146 



The Microphone. — Thos. S. Tait 146 



Leaf-bheaths and the Growth of Plants.— John Munro . ... 147 



Hornets. — W.\i. Wilson Saunders 147 



Equine Sagacity. — M. Carey-Hobson 747 



Colour-Blindness.— Dr. W. Pole, F.R.S 148 



Magnetic Storm, May 14, 1878. — Henry C. Manck 148 



" Measuring the Height of Clouds." — J. F. Wilke i.t8 



The Weather.— G. S. Thomson 148 



The Last Expeki.ments with the 80-ToN Gun 148 



The Registrarship of London University 149 



About Fishes' Heads. By Prof. E. Perceval Wright .... 149 



The Brown Institution 151 



On some Improved Methods of Producing and Regulating 



Electric Light. By H. Wilde (With Illustration) 152 



Influence of the Straits of Dover on the Tides op the 

 British Channel and the North Sea. By Sir Willi.\.m Tho.m- 



S.ov(,Y.^.S. {With Illustration) I5^ 



Our Astkono.mical Column : — 



Occultations of Stars by Jupiter's Satellites 154 



Occultation of 64 Aquarii by the Planet Jupiter iS4 



The Conjunction of Mars and Saturn, June 30, 1879 154 



Biological Notes : — 



Natural Selection among Salamanders . . . . » '55 



The Muscles of the Mammalian Foot '55 ; 



Sensitive Organs in Asclepiadaceje '55 : 



The Inhalation of Phosphuretted Hydrogen i55 



Structure and Affinities of Characese '^6 j 



Geoqrapmical Notes '5^ ' 



The Co.mpound Nature of the Elements '^' ,' 



Notes - '5^ ^ 



On Heliotropism in Plants *^* j 



Societies and Acade.mies • '^' i 



