with 80,000 volts when we have them at the civilized end of the wire? Imagine a domestic servant going to dust an electric lamp with 80,000 volts on one of its metals! Nothing above 200 volts ought on any account ever to be admitted into a house or ship, or other place where safeguards against accident cannot be made absolutely and forever trustworthy against all possibility of accident. In an electric workshop, 80,000 volts is no more dangerous than a circular saw. Till I learned Faure's invention I could but think of step-down dynamos, at a main receiving station, to take energy direct from the electric main with its 80,000 volts, and supply it by secondary 200-volt dynamos or 100-volt dynamos, through proper distributing wires, to the houses and factories and shops where it is to be used for electric lighting and sewing machines and lathes and lifts, or whatever other mechanism wants driving power. Now the thing is to be done much more economically, I hope, and certainly with much greater simplicity and regularity, by keeping a Faure battery of 40,000 cells always being charged direct from the electric main, and applying a methodical system of removing sets of 50 and placing them on the town-supply circuits, while other sets of 50 are being regularly introduced into the great battery that is being charged, so as to keep its number always within 50 of the proper number, which would be about 40,000 if the potential at the emitting end of the main is 80,000 volts.

Malleable Iron.-M. Forquignon has published an extensive series of researches upon malleable iron and the re-heating of steel. Among other conclusions he attaches special importance to the following: 1. Malleable iron always contains amorphous graphite; 2. A casting may lose carbon and yet remain brittle if the original quantity of graphite is not increased; 3. A casting may become malleable without losing any sensible portion of its carbon; 4. If silicium is added to manganesian castings they are improved by re-heating; 5. Hydrogen and nitrogen may unite with the carbon of a casting so as to make it malleable without the production of graphite; 6. The breaking load is always more than doubled, sometime more than quadrupled, by annealing. It increases with the duration of the heating, very rapidly at first and then very slowly; 7. Ductility generally increases with the resistance to breaking, but after a certain limit it has a slight tendency to diminish.-Ann. de Chim. et de Phys. C. WHOLE NO. VOL. CXII.-(THIRD SERIES, Vol. lxxxii.)

25

RADIO-DYNAMICS: ANOTHER VERIFICATION OF

PREDICTION.

By PLINY EARLE CHASE, LL.D.

On the 4th of October, 1878, I presented a communication to the American Philosophical Society,* in which I showed that the position of Watson's first intra-mercurial planet, as computed by Gaillot and Mouchez, represented the third intra-mercurial term of my harmonic series. At the last meeting of the British Association, Prof. Balfour Stewart read a paper in which he gave indications of sun spot disturbances by a planet revolving in 24-011 days and consequently having a semi-axis major of 163. This confirmation, both of my own prediction and of the calculations of the French astronomers, is the more interesting because the first confirmation of my series was contained in a communication which was made to the Royal Society, by Messrs. De la Rue, Stewart and Lowry; forty-one days after I had announced the series to the Philosophical Society and published it in the New York Tribune. The accordances are as follows: 1st interior harmonic term, 267 De la Rue, S. and L., Gaillot and Monchez, Stewart,

за

66

•165

267

•164

•163

New Experiments in Harmonic Vibration. Decharme mixes a little finely powdered minium in water and covers a horizontal plate of glass with it as uniformly as possible. He then lets fall upon this thin layer a drop of the mixture, and there appears a regular figure formed of the minium, arranged in rays and concentric rings, the whole producing very various designs. The figures resemble in many respects the vibratory forms of circular plates, which he has been studying. The three systems of the Chladni plates, the diametral, circular and compound, are usually coexisting, but either one can be made to predominate over the others at the will of the experimenter.-Comptes Redus.

*Proc. Am. Phil. Soc., xviii, 34-6.

† Ibid., xiii, 238.

Ibid., p. 470.

C.

Radiant Matter.-Father Serpieri and Prof. Riglio have published, in the Revista Scientifico-Industriale, some of their observations upon Crookes' apparatus. Ferrini has repeated the experiments and published the following theory: On account of the very great resistance which, as Hittorf has shown, is produced under the influence of a great rarefaction around the cathode, there arises a powerful induction, and the phosphorescence of the walls of the globe indicates their intersection with the lines of force of the electric field, which is most neatly circumscribed where those lines are the most energetic. The gaseous molecules arrange themselves along those lines while transmitting the electricity. The blue pencil, which corresponds to the most intense portion of the electric field, represents a continuous discharge between the cathode and the glass which is in front of it.-La Lumière Electrique.

C.

Phosphorescent Alumina.-Crookes has experimented with phosphorescent spectra in a nearly perfect vacuum. After operating for a long time upon chemically pure alumina, which had been precipitated from the sulphate, he noticed a curious phenomenon. When the alumina was first enclosed in the vacuum it was of a snowy whiteness, but after having been exposed frequently to the molecular current, which made it phosphorescent, it gradually assumed a rosy tint, and after two years, when it was exposed to the solar light, it showed a trace of the aluminium line. Repeated molecular excitement gradually brings the amorphous powder into a crystalline form. If ammonia is added in great excess to a diluted solution of alum a part of the alumina is precipitated. If the solution is then filtered and boiled, the alumina which was dissolved by the ammoniacal excess is precipitated. Separating it by filtration, igniting it, and submitting it to the action of the molecular current, instead of giving a red light it has a pale green phosphorescence which, when examined with the prism, shows no lines, but simply a concentration of light in the green portion of the spectrum. In studying rubies, of which he examined an enormous number by his apparatus, Crookes had the good fortune to find a single crystal, which, although it presented no difference to the sight, gave a green light under the action of the molecular current. This green light, however, always had a trace of the red line, and if the action of the molecular current was continued for several minutes the green phosphorescence faded and a red tint was produced. -Ann. de Chim. et de Phys.

C.

Radiant Absorption of Carbonic Acid. By experiments upon the absorption of radiant heat by gases, E. Lechler finds that a layer of carbonic acid 917 millimetres (37 in.) thick absorbs 90 per cent. of the luminous radiation. The carbonic acid of our atmosphere is therefore sufficient fully to account for the atmospheric absorption of the Sun's rays.-Ann. d. Physik. C.

Illumination of Tubes by the Holtz Machine.—The Geissler tubes can be illuminated by the Holtz machine, but the light is weak; in order to give it brilliancy, condensers and frequent interruptions of the current are required; if stratifications are desired it is necessary to interpose resisting media. Most of the experiments with the Crookes tubes can be performed with the Holtz as well as with the induction coil. Some of the experiments, however, which require very strong coils, are not very satisfactory: such, for example, as the luminous cross, the repulsion of two rays of radiant matter, and the incandescence of platinum.-Les Mondes.

C.

Constitution of Comets.-M. Prazmowski concludes, from observations since 1858 by the spectroscope and polariscope, that comets are formed of a condensed portion, which constitutes the nucleus, surrounded by an incandescent gaseous atmosphere, which contains carbon and reflects the solar light, and of a swarm of disaggregated material which is not controlled by the cometary attraction but moves in obedience to universal attraction. In some comets the polarization of the light is strongly marked, while in others it is almost wholly absent. In the latter case he compares the structure to that of atmospheric clouds.- Comptes Rendus.

C.

Connection between Refraction and Absorption of Light. -Ketteler has conducted an extensive series of experiments in order to prove his hypothesis that the refraction and absorption of light are due to the same physical laws. In order to strengthen his results, he tested each both by spectral, metric and photometric methods, and thus was able to show a very satisfactory accordance between the refraction and absorption curves. Each class of constants was found to exhibit the same relations to the concentration of the liquids which were experimented upon, and he regards the experiments as conclusively establishing the identity which is assumed in his hypothesis.― Wiedemann's Annalen.

C.

Book Notices.

WORKING DRAWINGS AND HOW TO MAKE AND USE THEM, designed for Industrial, Technical, etc., Schools and Artisans desiring a knowledge of the principles of Pattern and Template making. By Lewis M. Haupt, Professor of Civil Engineering in the University of Pennsylvania, etc. 12mo. Philadelphia: Jos. M. Stoddard & Co. 1881.

MR. EDITOR:-Having been absent from the city, I have only just received the August number of the Journal, which contains a review of my recent little book on "Working Drawings," etc., and as your author has manifestly misunderstood my preface or read it hastily, I desire to correct some of the erroneous impressions his review must create, to the prejudice of the work.

*

He states first generally that "Engineers and master mechanics * have been amazed that even graduates of technical and scientific schools generally come to them with entirely erroneous methods of thought and practice."

If this statement be true, then the system of instruction in our scientific and technical schools generally must be out of gear, from the use of present standard authorities, not the book under review, as that has not yet been introduced, and it is time the schools should know it and change their system; but I have heard no complaint in that direction, and our graduates seem to have no difficulty in making drawings that are readily understood. At all events, no school should teach errors, and if our system be such we hope to be convinced of it that a change may be immediately effected.

In the second paragraph your reviewer states that "The title and preface of this book give the impression that the author has done a good work in presenting a plan by which cadet engineers can be graduated capable of entering the draughting room and being immediately useful," etc.

If such an impression is created by a careful reading of the preface I must confess that I need to study how to write correctly, for I have distinctly stated therein that the book was designed especially for the very lowest grade of scholars capable of comprehending the subject, viz., those in the public schools, and that this book was but the first of a series and was intended simply as a test of the ability of the

The italics are my own.