172 



NATURE 



{Dec. 21, 1876 



buttons held in their positions by rigid rods or elastic strings, 

 according as they represent layers of a conducting or non-con- 

 ducting substance. When considered in connection with thermo- 

 electricity, the buttons are assumed to oscillate on the cord, and 

 if they move in one direction with greater velocity than in the 

 other, the cord will tend to move in the former direction. Now 

 at a junction of copper and iron an unsymmetrical oscillation of 

 the molecules must ensue, and the cord, or electric current, will 

 advance when two junctions are at different temperatures. Mr, 

 Ivodge showed experimentally that for a given difference of 

 temperature the maximum thermo-electric current is obtained 

 when one of the junctions is at 280° C, and beyond this point 

 the amount of deflection decreases. This fact led Sir W. 

 Thomson to discover the convection of heat by electricity ; 

 that is, if we have a circuit composed of copper and iron 

 and one of the junctions be at the above temperature, the cur- 

 rent in passing from hot to cold in the iron, or from cold to hot 

 in the copper, absorbs heat. This fact was experimentally illus- 

 trated by Mr. Lodge. A strip of tin plate is symmetrically bent 

 so as to nearly touch the two faces of a thermopile and is heated 

 at the bend by steam passing through a brass tube on one side 

 (not end) of the thermopile and kept cold by a current of water 

 on the other side. As the arrangement is symmetrical no current 

 is found to pass through the thermopile, but when a powerful 

 voltaic current passes through the strip of metal, a distinct de- 

 flection of the needle is observed in accordance with the above 

 law. 



Philadelphia 



Academy of Natural Sciences, June. — Prof. Cope's fourth 

 contribution to the history pf the existing Cetacea, describes new 

 r.pecies of Globiocephalus, Phoccena, and Lagenorhynchus. He 

 also described (July 25) a new fossil genus of Cameiidae, Proto- 

 labis, with three upper incisors on each side. 



Paris 

 Academy of Sciences, December ix. — Vice- Admiral l^aris 

 m the chair. — The following papers were read : — Theorems 

 relating to couples of segments miking a constant length, taken 

 the one on a tangent of a curve, and the other on a normal of 

 another curve, the two curves being of any order and class, by 

 M. Chasles.^ — On the composition of glass and crystal among the 

 ancient?, by M. Peligot. He proves by quota'ion and chemical 

 analysis that the glass of the ancients differed importantly in 

 composition from the ordinary glass of to-day ; the proportion 

 of lime was much smaller (our good glasses contain 12 to 15 

 per cent, of the r weight of it). Further, no test or analysis 

 proves that the true crystal, the English flint glass, was known 

 to the ancients. The honour of its invention belongs to us. — - 

 General method of analysis of the tissue of plants, by M. Fremy. 

 He finds the principal tissues of plants, after exhaustion by neu- 

 tral solvents, to be formed by organic association of (i) ceilulo- 

 ric bodies (cellulose, paracellulose, metacellulose) ; (2) vasculose ; 

 (3) cutose, (4) pectose, (5) pectate of lime, (6) azotised substances, 

 (7) various mineral matters. He indicates the reagent for each. 

 — On a polymer of oxide of ethylene, by M. Wurtz. — Results 

 obtained on phylloxerised vines by their treatment with sulpho- 

 carbonates, manures, and compression of the ground, by M. 

 Mares. — -M. ds Lesseps presented a report by M. Roudaire on 

 the results of his exploration of the Tunisian Chotts. An extract 

 from an Arab'c manuscript found at Nafta shows that the sea at 

 one time reached to that place. M. Roudaire points out the ad- 

 vantages of the new project. — On the laws of impulse {entraine- 

 ment) in plants, by M. Baillon. — A new chapter added to the 

 history of hybrid Aigilops, by M. Godron, — Researches on 

 the structure, the modes of formation, and some points relative 

 to the functions of the urns in Nepenthes distillatoria, by M. Faivre. 

 The urn is a special formation, sui generis, belonging histologi- 

 cally to the foliaceous type, derived from the peduncle, which 

 itself is a continuation of the median nervure of the foliar lamina. 

 The complex liquid of the urns proceeds from the plant itself; and 

 liquid poured into the urns is partly absorbed. — On the caries of 

 bones, by M. Brame. — Researcheson the vitality of the eggs of 

 phylloxera (third communication), by M. Bdbiani. The upper 

 limit of temperature, at which the eggs are rendered sterile, is 45°. 

 (The experiments were made with hot water.) The eggs and 

 insects brought out of the ground die quickly on being exposed 

 in a dry place. The eggs by (reason of the chitine of their outer 

 envelope) present much greater resistance to destructive agents 

 than the individuals fully developed ; and the germ or embryo 

 is less surely affected by large doses of poisonous vapour acting 

 for a short time, than by small doses, acting slowly and con- 



tinuously. — On some processes indicated by Florentinus, for pre- 

 servation of the vines and for the manufacture of wines, by M. 

 Paulet. — On the geometric construction of the pressures which 

 are borne by several plane elements v/hich cross at the same 

 point of a body, by M. Boussinesq. — Note on the integration of 

 the equation — • 



{xdy -ydx)(a -t- bx Vc}>)-dy{a' ■\-b'x^c'y)-\-dx{a" + b" x-^ c")'\—0, 



by M. Allegret. — On the spectrum of the new star of the con- ' 

 stellation of Cygnus, by M. Cornu. [See separate article. ] — Note 

 on the correction of variations in the working of astronomical 

 pendulums arising from differences of atmospheric pressure, by 

 M. Redier. Above the bob is fixed an aneroid barometric case, 

 and a mass connected with the flexible wall of this rises or falls, 

 thus compensating the effects of the pressure. — Note on the 

 theory of the radiometer ; extract from letter of Mr. Crookes to 

 M. du Moncel. — Liberation of ammonia observed after rupture 

 of certain bars of steel, by M. Barre. This was verified with 

 red litmus and yellow turmeric paper ; which applied to the 

 moistened fracture, changed to blue and brown respectively. 

 Bubbles of gas rose from the moistened surface during a quarter 

 of an hour. The effect is got in Bessemer steels, and in steels 

 obtained from the Siemen's furnace. M. Daubrea remarked that 

 M. Fremy had observed the liberation of ammonia from .steels 

 in the cold state in presence of steam. M. Boussingault had 

 discovered nitrogen in all the meteoric irons he had ex- 

 amined, and M. Cloez had found ammonia in the state of chlor- 

 hydrate and carbonate, in the meteorites of O.-^gueil. He thinks 

 the gaseous bubbles indicated also the presence of a gas less 

 soluble in water than ammonia. — Researches on the urea of 

 the blood, by M. Picard. There are in arterial blood two dif- 

 ferent substances, both decomposed by Milon's reagent ; the 

 one, very destructible, disappears almost completely in the cipil- 

 laries ; the other is fixed, resistant, and exists in venous blood in 

 the same quantity as in arterial (it is probably the urea of the 

 blood). — On the fixed cells of tendons, and their lateral proto- 

 plasmic expansions, by M. Renant. — On a dust shower at 

 Boulogne on October 19, and on the mode of formatioi of earthy 

 rains in general. The dust was mostly of debris of various 

 microscopic algae, with grains of silica and lime ; it was probably 

 raised from the beach. He thinks the organic matter in such 

 showers is not, as often supposed, derived from the air. — The 

 height of the quaternary glacier of La Pique, at Bxgneres-de- 

 Luchon, by M. Piatte. 



CONTENTS pagb 



Graham's Researches. By W Chandler Roberts, F.R.S. . . 153 



The Andes and thk Amazon 154 



Our Book Shelf: — 



C^rrick's " Secret of the Circle, its Area Ascertained" .... 155 



Smith's ' Impo.^sible Prob'em" 155 



Burrows and Coiton's "Concise Instructions in the Art of Re- 

 touching" 156 



Lbttkrs to the Editor : — 



Sea Fisheries. — Pro*". Alfred Newton, F.R.S 156 



Ocean Currents. — Rev. W. Clement Lev 157 



Solar Physics at the Present Time. — Prof. Piazzi Smyth . . . 157 



Radiant Points of Shooting Stars.— William F. Drnning . . . 158 



The Atlantic Ridge and Distribution of Fossil Plants — M. . . . is^ 



Antedon Rosaceus (Comatula Rosacea). — W. R. Hughes, F.R S. 158 



"Towering" of Birds.— F. W Millett 158 



The Spectru.m of the New Star. By Prof. A Cornu(W''/M IUiis- 



traiion) 15S 



Just Intonation 159 



Anatomy OF the Teeth (With Illustrations) 161 



Formation of Raindrops and Hailstones. By Fro^ Osborne 



Reynolds. MA. (With Illustrations) 16 j 



D'Aldertis's Expedition UP the Fly River, New Gui.N'EA ... 165 

 Our Astronomical Column : — 



The New Star in Cygnus 166 



Remarkable Star Spectrum 166 



The Minor Planet, No. i6q 166 



Newcomb's Corrections to Hansen's Lunir Tables 166 



Prof. Forster's Scientific Lectures 167 



Chemical Notes ; — 



Variations in the Critical Point of Carbon Dioxide in Mineral.s, and 



Deductions from these .and other Facts 167 



ThermoChemical Researches 1(7 



Theiae in Tea 167 



Influence of Pressure on Combustion 167 



Biological Notes : — 



The American Bisons 167 



Coloration of Water by Salpsc 168 



The Evolution of the Camelidse 168 



Self-Fertihsation ol Plants ■ ■ •. '^8 



An Unu-ual Case of Natural Selection 168 



Gelatine in Relation to Nutrition . . 168 



Notes 1&8 



Scientific Sermls 171 



Societies and Academies 171 



