532 



NATURE 



[September 29, 1892 



more observations and experiments to decide this important 

 question, as "while there is no proof, there is a strong pre- 

 sumption that X. perforans cannot begin the attack." Still there 

 is much difference of opinion, as the Trinidad Commission, 

 which investigated the subject, " believes that the beetle is the 

 primary cause of the disease, and that it is immaterial whether 

 the cane is healthy or not ; " others believe that it is only canes 

 which are " already physically weakened by other causes which 

 are attacked by it. " 



The Transparent Cane and Caledonia Queen enjoy an entire 

 immunity from the attack, "even when growing side by side 

 with badly infested Bourbon canes, and varieties raised by seed 

 show no signs of being attacked." It is therefore suggested 

 that perhaps the Bourbon cane, enfeebled by long cultivation on 

 the same lands and degenerated by careless ways of propagation, 

 has become powerless to resist the attacks, and planters in their 

 investigation must consider the possibility of attacks "being 

 favoured by constitutional weakness which in no way implies 

 -want of care in cultivation, but perhaps the reverse." 



The enemies of the shot borer are still to be found. 



An important lesson taught by this report to the planter is 

 the necessity of varying the description of canes grown and the 

 great value of the new seed canes raised in Barbados. 



S. N. C. 



SOCIETIES AND ACADEMIES. 

 Paris. 

 Academy of Sciences, Sept. 19. — M. Duchartre in the 

 chair. — On the white rainbow, by M. Mascart. This phe- 

 nomenon, usually known under the name of Ulloa's circle, is ex- 

 plained, not on the untenable assumption of water vesicles, 

 but of very minute drops as constituting the mist upon which 

 it is seen. The diminution of the diameter of the drops causes 

 a displacement of the first maximum of the interference fringes 

 which produce the supernumerary arcs. The relative intensities 

 of the various colours retain equal values long enough to make 

 the rainbow appear achromatic, with perhaps a slight red colora- 

 tion along the outside. The radius of such a circle has been 

 known as small as 33° 30'. — Observations of the new planet 

 Wolf (1892, Sept. 13), and of the planet Borrelly-Wolf (Eri- 

 gone ?), made at the observatory of Paris (west equatorial), by 

 M. Bigourdan. — On a recurring series of pentagons inscribed to 

 the same general curve of the third order, by M. Paul Serret. — 

 On the production of the spark of the Hertz oscillator in a 

 liquid dielectric instead of air, by MM. Sarasin andDe la Rive. 

 The two balls of 3 or 4 cm. in diameter, between which the 

 Ruhmkorff discharge takes place in the Hertz oscillator, were 

 plunged into an insulating fluid. This was, in the first place, 

 olive oil, contained in a cylindrical vessel, 20 cm. in diameter, 

 pierced laterally to admit the end branches of the oscillator. 

 Sparks I cm. long were obtained, giving a characteristic sound, 

 louder than that of a discharge through air. The effect on the 

 resonator is notably increased by the arrangement, most brilliant 

 sparks being produced. The interferences of the electric force 

 by reflection from a plane metallic surface give the same 

 results as in air. During the discharge, the oil is 

 carbonized and loses its transparency, but without affect- 

 ing the intensity. Similar experiments were made with 

 essence of terebenthine and petroleum, but the oil 

 proved the safest and most advantageous medium. — 

 The action of bromine in presence of aluminium bromide on 

 the cyclic chain carbon compounds, by M. W. Markovnikoff. 

 It has been shown that a small quantity of bromide or chloride 

 of aluminium added to the bromine produces a vivid reaction 

 -with the carbon compounds of the aromatic series, usually 

 resulting in substitution-products of a crystalline form. Further 

 experiments show the generality of the reaction for all the 

 hydrocarbons of the series CnHon which were examined. It 

 has been studied chiefly as regards the naphthene (hexacarbon) 

 series, and may be expressed by the general equation — 



C8Hi2-nBw -{- Bri2-n = CgBe-n + 6HBr. 

 The rule seems to be that the action of the bromine on the 

 naphthenes at the ordinary temperature takes place principally 

 on the hydrogen atoms of the cyclic chain, transforming them 

 into benzene nuclei, in which all the hydrogen atoms are re- 

 placed by bromine, whilst the lateral chains remain intact. It 

 is found that besides the bodies of the aromatic and naphthene 

 series, the hydrocarbons of the paraffin series also react easily in 

 presence of AlBr3. — The rotatory power of fibroin, by M 



NO. I 196, VOL. 46] 



Leo Vignon. — Experimental researches on the bulb centre 

 of respiration, by MM. J. Gad sand G. Marinesco. — In- 

 fluence of continuous and discontinuous electric light upon the 

 structure of trees, by M. Gaston Bonnier. Out of three lots of 

 plants, one was submitted to a constant electric illumination, 

 another to an illumination alternating with twelve hours' dark- 

 ness, and a third was left to develop in ordinary daylight. The 

 experiments were carried out in the electric pavilion of the 

 Central Markets at Paris. The temperature was pretty constant 

 (between 13° and 15°) ; the light was given by arc lamps in 

 shades, and the trees — pines, beeches, oaks, and birches — were 

 surrounded by glass, the dir being gradually renewed. It was 

 found that continuous electric light produced considerable modi- 

 fications of structure in the leaves and shoots of the trees. The 

 plants breathed, assimilated, and secreted in a continuous 

 manner, but they appeared as if encumbered by this continuity, 

 and showed a simpler structure. The shoots were very green, 

 the leaves more open, less firm, and smaller. Differentiation 

 was less decided in every respect. In the specimens exposed to 

 intermittent illumination the results were very similar to those 

 obtained under normal conditions. — On the discovery of the line 

 of no declination, by M. W. de Fonvielle. From an inspection 

 of geographical maps preceding or contemporaneous with the 

 discovery of America it appears certain that Columbus was the 

 first to discover the variation of the compass. Indeed, it was 

 the rapidity with which the observed declination diminished 

 which produced consternation among his seamen, whom he could 

 only save from a panic by persuading them that the pole star had 

 changed its place, while the needle remained a true guide. The 

 stratagem succeeded, but Columbus suspected that the radius of 

 curvature of the earth was different at the Sargasso sea, and that 

 the line of no declination represented a natural frontier between 

 the territories of Europe and Asia. This natural frontier was 

 adopted by the Pope Alexander VI. in his division of the new 

 world between the rival aspirants. Columbus himself found 

 that the line did not coincide with a meridian during his third 

 voyage, but the illusion guided even Magellan, and was only 

 dispelled by Halley's magnetic chart in 1700. 



CONTENTS. PAGE 



The Speech of Monkeys. By C. LI. Morgan . . . 509 



Bee-keeping. By W. Tuckwell 510 



A New Course of Chemical Instruction. By 



J. W. R 511 



Our Book Shelf:— 



Molisch : "Die Pflanze in ihren Beziehungen zum 



Eisen."— W. B. H 512 



Mockler-Ferryman : " Up the Niger " 512 



Letters to the Editor : — 



Density of Nitrogen. — Lord Rayleigh, F.R. S. . . 512 

 Recent Spectroscopic Determinations. — G. John- 

 stone Stoney 513 



Printing Mathematical Symbols. — Prof. Silvanus P. 



Thompson, F.R.S 513 



A so-called Thunderbolt.— Dr. Oliver J. Lodge, 

 F.R.S. ; George H. Hewitt ......... 513 



Peripatus Re-discovered in Jamaica. — M. Grabham 



and T. D. A. Cockerell 514 



Reflection on Valley Fog.— J. Edmund Clark . . . 514 



Impure Water in Bread.— W. M. F P 514 



The Comets of Brorsen (1846 VII.) and Brooks 

 (1892 "^").—W. F. Denning ... . . 514 



Note on the Progress of the Dioptric Lens as used 

 in Lighthouse Illumination. {With Diagrams.) By 



Charles A. Stevenson 514 



Modern Dynamical Methods. By A. B. Bassett . 516 

 The Passage of Granite Rock into Fertile Soil. 



{With Diagram.) By Alexander Johnstone . , . . 517 

 The Imperial Institute at St. Petersburg. By M. 



Armand Ruffer 520 



Notes 520 



Our Astronomical Column : — 



The Variation of Latitude at Pulkova 524 



Double Star Observations 5^4 



Solar Observations at Rome 5^4 



Geographical Notes 525 



The Iron and Steel Institute 525 



Fuels and their Use 527 



Sugar-cane Borers in the West Indies. By S. N. C. 531 

 Societies and Academies 532 



