572 



NATURE 



{Oct. 9, 1879 



and ihe same quantity of heat will (low across all sections which 

 lie in the same vertical. In this case the flow across a horizmtal 

 area of unit size will be equal to the product of the temperature 

 gradient by the conductivity, if we employ the latter term in an 

 extended sense so as to make it include convection by the perco- 

 lation of water, as well as conduction proper. It follows that 

 in comparing different strata lying in the same vertical, the 

 gradient will vary in the converse ratio of their conductivity. 

 It seems probable that the same law of inverse proportion 

 between gradient and conductivity holds approximately even 

 when the strata compared are not in the same vertical but 

 are widely distant. 



As regards the modes of ob.servation which have been 

 employed for the determination of gradients ; — shafts full of 

 water, and wells of large diameter, afford so much facility 

 for equalisation of temperature by currents between the colder 

 water above and the war}ner water below, that they furnish no 

 useful results. Even in bores of small diameter the same 

 disturbing cause exi>ts and always makes the observed less 

 than the true gradient. 



Observations in mines will be vitiated by the presence of 

 pyrites which generates heat by its slow combustion, and are 

 also liable to be vitiated by strorg currents of air ; but when 

 they are taken at the newly exposed face of a gallery wliich is 

 being driven into the rock, care being taken to prevent strong 

 air-currents at the place, and the surrounding ground not being 

 too much honeycombed by previous excavations, good re^ults 

 may be obtained. A hole should be bored to the depth of 

 about two feet in the newly exposed face, the thermometer 

 inserted, and the hole plugged with clay. 



SCIENTIFIC SERIALS 



American jfoHrnal of Science and Arts, September. — In the 

 opening paper, on the pertinacity and predominance of weeds. 

 Prof. Asa Gray, from an examination of European weeds whicli 

 have taken a strong hold on the United States, opposes Mr. 

 Henslow's view that plants best fitted for domination as weeds 

 are in general self-fertilised plants, and owe their predominance 

 to this. He also regards the "greater plasticity " assumed by 

 Prof. Claypole for European as compared with American plants 

 as purely hypothetical. — In view of the variations in amount of 

 oxygen in the atmosphere of a given place (sometime, by as 

 much as one-fortieth of the average, and often the one-hundredth 

 or two-hundredth part). Prof, jlorley calls in the theory by 

 which Prof. Loomis accounts for certain great and sudden de- 

 pressions of temperature at the earth's surface, viz., by vertical 

 descent of cold air from the higher parts of the atmosphere. 

 The lower air at such times might ^^■elI contain a less proportion 

 of oxygen than the average. Pending systematic observations 

 at points Prof. Loomis has indicated, the author here de.-cribes 

 at length his method of analysis, and the results of observation 

 on samples of air collected at home ; these seem to lend some 

 support to his theory, — A remarkable meteorite fell at E-.ther- 

 ville, Emnirl Co., Iowa, on May 10 ; one mass weighing 431 lbs. 

 was found fourteen feet under the surface of the ground in a 

 ravine, and, besides several small masses near, a mass of 151 lbs. 

 about two miles westward. Prof. Shepard, from specimens in 

 hand, regards this meteorite as a connecting-link between the 

 litholites and litho5iderites, unless it be placed as a separate 

 order in the Eucritic group of the former. — Prof. Marsh announces 

 the discovery of two new lower jaws belonging to the genus 

 Dryolestes (of Jurassic mammals). — Remaining papers : — On the 

 colour correction of achromatic telescopes, by Mr. Harkness. — 

 Reply to Principal Dawson on Eoziion canadense, by Prof. 

 Mobius. — Terminal moraines of the North American ice-sheet 

 (continued), by Mr. Upham. — New observations on planetoids, 

 by Mr. Peters, — Observations on the genus Macropis, by Mr. 

 Patton. 



SOCIETIES AND ACADEMIES 

 Paris 

 Academy of Sciences, September 29. — M. Daubree in the 

 chair. — The following papers were read : — On the development of 

 the pcrturbativc function in the case where, the eccentricities being 

 small, there is any mutual inclination of theorbits, by M. Tisserand. 

 — Construction of the international geodetic standard, and deter- 

 mination of its controlling weights, by MM. Sainte-Claire 

 Deville and Debray. The method is given in detail. — Studies 

 on the effects and mode of action of sutistances employed in 

 antiseptic dressings, by MM. Gosselin and Bergeron. The 



method was to put blood, then pus, in contact with various 

 antiseptic agents (including solutions of carbolic acid of various 

 strength, camphorised alcohol, camphorised brandy), and noting 

 the effects, both with the naked eye and with the microscopt^ 

 The antiseptic agent was in some cases put in glasses with the 

 blood or pus, sometimes applied by means or evaporation and 

 pulverisation. The result is specified in each case ; the 20 

 per cent, solution of carbolic acid, alcohol, and camphorised 

 alcohol, seem to have prevented putrefaction best. — Theoretical 

 essay on the law of Dulong and Petit ; case of solid and liquid 

 bodies and vapour.s, compound bodies, by M. Wiliotte.— Vibra- 

 tory forms of hubbies of glyceric liquid, by M. Decharme. A 

 bubble is supported on a thin watch-glass fixed at the end of a 

 vibrating plate or rod ; it follows and amplifies the vibrations, 

 and with favourable conditions one can see distinct nodes and 

 ventral segments, whose number varies with the velocity of 

 vibration and diameter of tlie bubble. Three laws are given : 

 (I) With a given number of nodals, th; diameters of the bubbles 

 are proportional to the lengths of the vibrating plate, or 

 inversely proportional to the square roots of the numbers 

 of vibrations. (2) With a given diameters of bubbles, the 

 numbers of ncdals are inversely proportional to the lengths of 

 the vibrating plate, or directly proportional to the square roots 

 of the numbers of vibrations. (3) With a given length 

 of vibrating rod, the numbers of nodals are proportional to the 

 diameters of the bulbs. These experiments generalise that of 

 Melde by extending it to spherical surfaces, and even to volumes, 

 for the author has found that thin balloons of caoutchouc filled 

 with water behave like bubbles. — On the presence of alcohol in 

 the animal tissues during life and after death, in the case cf 

 putrefaction, from the physiological and toxicological point cf 

 view, by M. Bechamp. Horse-flesh (3 kg.) plunged for ten 

 minutes in boiling water, to coagulate the surface, then inclosed i > 

 a vessel, was examined after a month. About o'8 gr. of alcohol wa s 

 got from the interior, and 10 gr. of salts (acetate, butyrate, &c.) cf 

 soda. (There were numerous bacteria ; no vibrion.) 4 kg. left 

 to itself four days gave less alcohol. Thus putrefaction is essen- 

 tially similar to fermentation ; ar.d specially so to butyric. M. 

 Bechamp also found alcohol in various healthy animal tissues 

 (brain, muscles, and liver). — Action of sulphideof carbon liberated 

 in a slow and prolonged way on the vine, by M. Rohart. This 

 is more efficacious than the brief application, and does not 

 injure the plant. — Discovery of two small planets by Mr. Peters. — 

 Action of metallic nitrates on monohydrated nitric acid, by M. 

 Ditte. — Thermal study of succinic acid and its derivatives, by 

 M. Chroustchoff. — On a new curare extracted from only one 

 plant, Strychnos triplinervia, by MM. Couty and De Lacerdc . 

 This is less active than the other, but easy to obtain in larg3 

 quantity. It gives in a few seconds a curarisation which mav hz 

 arrested in its different periods. 



CONTENTS Pack 



Education 5. 9 



The Capercaillie in Scotland 5;:o 



Our Book Shelf: — 



Hassall's '* San Remo and the Western Riviera, Climatically and 



Medically Considered " - i 



Letters to the Editor: — 



An Index to Zoological Genera. — Samuel II. Scuddhr . . . . 5; i 



The Mineral Waters of Hungary. — J. Beknath 5*1 



Does Sargassum Vegetate in the Open Sea. — Dr. Otto Kuntzb . 3=2 



A Liquid Rheostat. — Frederick John Smith (tp-'it/t Dittgrams) 552 



The Carving of Valleys. — ^Jas. Durha.m 552 



The Bis-cobra, the Goh-samp, and the Scorpion. — Dr. H. F. 



Hutchinson 5: ^ 



Certain Animal Poisons. — Dr. H. F. Hutchinson 5^- 



Spider's Web, New Caledonia. — Capt. S. P. Oliver -fa 



Change of Colour in Frogs. — W. J. Cha.mberlayne 5:4 



Subject-Indexes to Transactions or Learned Societies. By 



Richard Garnktt 564 



On Variable Stars 555 



Coffek-Leaf Disease of Cevl'v ■ , j-jthern India. By D. 



Morris 557 



Our Astronomical Column: — 



The Satellites of Mars 5:^9 



The Satuniian Satellite, Mimas 560 



The Minor Planets 560 



Geographical Notes • , . 560 



Notes j^t . 



On the Gradual Conversion of the Band Spectrum of Nitro- 

 gen into a Line Spectrum. By Prof. WOllner 564 



K Historical Skhtchofthr Various Vapour-Density Methods. 



By Jas.T. Brown, F.C.S 565 



Electricity as a Motive Power. By Prof. W. E. Ayrton ... 568 



The Antiquity of Man 571 



Underground Te.mperature. By Prof. J. D. Everett, F.R.S. . 571 



Scientific Serials 572 



Societies and Academies 572 



