SCIENTIFIC NEVS^S. 



[Mar. 1 6, 1888. 



kinds of wood are sawn very fine, as if for veneers, and 

 paper is pasted over one side. The whole is passed 

 under rollers, and in this manner a sheet is produced 

 scarcely thicker than ordinary paper-hangings, and very 

 easy to apply. The paper side is turned towards the 

 wall. These compound hangings may be varnished and 

 polished like wood. 



The Pith in Pine-Trees. — M. Emile Mer has sub- 

 ■mitted to the Academy of Sciences of France an elaborate 

 memoir on the conditions of growth of coniferous trees. 

 The pith is not always in the centre, because the rings 

 f annual growth have not a constant thickness. The 

 .auses of this irregularity are slope of the ground, the 

 exposure, the proximity of other trees, and the eifects of 

 injui-ies. Trees whose layers of growth are very 

 irregular yield generally wood which is not homo- 

 geneous, since its elements have neither the same 

 distribution nor the same structure. Hence the technical 

 properties of the timber are modified, and its industrial 

 value is reduced. 



Colour-Dispersion of the Eye. — A simple method for 

 demonstrating this phenomenon has been indicated by 

 O. Tumlizz (Pfliiger's Archiv and Humboldt). For this 

 purpose an image produced only by the marginal parts 

 of the lens is most suitable. To cut out the central rays, 

 Tumfizz looks at a vertical ring formed of this platinum 

 wire, glowing at a white heat in a non-luminous gas-flame, 

 and moves an opaque screen with a round aperture about 

 half an inch in width, so far from the eye towards the 

 luminous ring as can be done without covering the 

 latter. The ring appears then outwards red, and within 

 violet-blue. The ring should be 4-5ths of an inch in 

 diameter, and the eye is directed to its centre. 



Symmetrical Distribution of the Centres of the 

 Four Main Continents. — M. Alexis de Tillo (Comptes 

 Rendiis) calculates that the orographic centre of Asia 

 and Europe is situate in latitude 43" N. and longitude 

 85^ E. ; that of Africa in 4'=' N. and 27° E. ; that of 

 North America in 45'-^ N. and 102" W., and that of 

 South America in 14" S. and 56° W. These four 

 centres form a nearly regular quadrilateral. The longest 

 side (92°) lies between the centres of Asia and Vorth 

 America ; the centre of Africa is 82" from that of South 

 America. The distance between the centres of the 

 double continents is approximately the same. The 

 geometrical centre of all these four centres is in the 

 region of the Azores. Hence the author considers the 

 meridian of Ferro the natural meridian of the globe. 



Underground Wires in New York. — We are pleased 

 to learn that good progress is being made in the conver- 

 sion of the present overhead to an underground system 

 of electrical wires in New York. It is indeed time that 

 the huge poles, covered with advertisements, and laden 

 with scores of wires, should no longer be allowed to 

 disfigure the handsome streets and buildings of this im- 

 portant city. It appears that under authority from the 

 Board of Electrical Control, a company is constructing 

 subways to be used by electrical companies on terms 

 impartially determined. The profits of the subway 

 company are not to exceed ten per cent, on the actual 

 outhy, any surplus going to the city. Under the new 

 law, as soon as a suificient length of subway has been 

 constructed in any district, the Board are required to 



give the electrical companies notice to remove their wires, 

 and if they neglect to do so within ninety days, the local 

 authorities are to remove them. We cordially approve 

 such measures being adopted, but in this country many 

 would consider them rather arbitrary ; but then, 

 of course, we are supposed to be less free, as well as not 

 being Republican. Provision is made for something like 

 13,500 miles of telegraph and telephone wires, 500 miles 

 for arc lighting and power, and about 100 miles for glow 

 lamps, and already some miles of the subway are in use. 



The Origin of the Phylloxera. — M. Zaborowski, 

 writing in the Revtie Scientifique, points out that all epi- 

 demics, whether among animals or plants are more de- 

 structive in countries where they have been recently 

 introduced than in their ancient seats, where the more 

 susceptible individuals have been in course of time elimi- 

 nated, and where the existing individuals are descended 

 from those of a more resisting character. Instances of 

 this appeared in the ravages of the cholera in its earlier 

 visits to Europe, in the deadly character of the small-pox 

 among the Eskimos, etc. This consideration supports 

 the view that the phylloxera is of American origin, and 

 that the American vines have by a process of natural 

 selection arrived at a high degree of immunity from the 

 attacks of this parasite. He shows that the remedies 

 proposed are not generally efficacious. Vines in low 

 grounds may be saved by flooding, and those in sandy 

 soils are not attacked. The chemical remedies have been 

 found effectual where they have been carefully applied, but 

 such application cannot be calculated on. The American 

 vines yield in general unsatisfactory wines, but their 

 use as stocks upon which superior European strains are 

 grafted has proved the best means of dealing with the 

 evil. Both the grapes and the wines thus obtained are 

 free from rankness(_/(7.r/'««ss), and compare favourably with 

 those grown on old European stocks. 



Artificial Rubies. — MM. Fremy and Verneuil have 

 recently' announced to the Academy of Sciences in Paris 

 that they have at length succeeded in preparing arti- 

 ficial rubies, which are in all the points of hardness, 

 colour, and crystalline form identical with those which 

 are found in nature. M. Desclorzeaux has examined 

 the crystals microscopically, and has expressed his 

 opinion that they agree, when submitted to this test, 

 with the properties of the real precious stones. The 

 matrix in which the rubies are embedded is of a soft 

 nature, so that the gems can easily be detached and 

 rendered of commercial value. The discoverers hope 

 that with larger apparatus and more improved appliances 

 for obtaining a greater heat in the furnace in' which the 

 operation is conducted, that they will be able to obtain 

 stones of a much larger size than those which they have 

 already prepared. M. Fremy has been for several years 

 engaged on this work, and as far back as 1877 suc- 

 ceeded in obtaining artificial rubies. He, in conjunction 

 with M. Feil, heated to bright redness in a fire-clay 

 crucible a mixture of alumina and red lead with a small 

 quantity of potassium bichromate. The crystals formed 

 were perfect in shape, but were frequently lamellar, and, 

 being inclosed in a hard matrix, it was found impossible 

 to extricate them. Alumina, according to the same 

 authors, when heated to a high temperature with barium 

 fluoride and a trace of potassium bichromate also yields 

 crystals which are identical with natural rubies. 



