Makch 9, 1883.] 



SCIENCE. 



145 



capable of furnishing regularly for three consecutive 

 hours the work of twelve to fifteen men, A balloon 

 of 900 cub. m. capacity covild raise in the air such an 

 apparatus with the additional load of two or three 

 men. M. Tissandier is now engaged in the conslruc- 



, tion of a gas-generator; after this is completed, he 

 hopes to construct an elongated balloon to which he 

 can apply his machinery. — {Eev. electr., Jan. 27, 

 1883.) J. T. [294 



Cost of electric lighting. — Dr. Siemens, in his 

 address to the London society of arts, showed that 

 arc-lamps were cheaper than incandescent lamps, and 

 that both would be decidedly cheaper than gas-light- 

 ing if the electric companies bad the opportunity to 

 make sufficiently large plants, and the gas companies 

 continued to pay their ijresent large dividends. — {Bev. 

 electr., Nov. 2.5, 1882.) J. T. [295 



Ne-w electric lamp. — Mr. Charles Lever of Man- 

 chester has invented and patented an electric lamp 

 in which the carbons are lield apart by a spring when 

 no current is passing. The current, when first started, 

 excites an electro-magnet which releases a clip, and 

 allows the upper carbon to fall iipon the lower; the 

 weakening of the magnets consequent on shunting 

 the current through the carbons allows the spring to 

 bind the clip, and draw back the upper carbon to the 

 proper distance. When the carbons burn away so as 



. to increase the resistance greatly, this process is re- 

 peated. — (Key. e'iectr., Jan. 6, 1883.) J. T. [296 

 Electric torpedo-boat. — A torj)edo-boat has just 

 been satisfactorily tried at Constantinople, in which 

 a Siemens electro-motor drives two screw propellers in 

 the rear of the boat. The vessel is cigar-shaped, and 

 moves under water at the rate of eight knots an hour. 

 Its path is traced in the day-time by a wire which 

 .projects above the surface, and is followed by a tele- 

 scope; in the night, by a lantern having an opening 

 only towards the shore, and a light too feeble to be- 

 tray itself to the enemy by reflection. The place in 

 which the torpedo-boat was tried furnished a severe 

 test on account of the strong currents, which vary in 

 direction in different parts of the channel, and in 

 strength from one part of the day to another. The 

 wires conveying the explosive discharge are, of course, 

 distinct from those carrying the motive current. — 

 {VEU'ctricile, Jan. a, ISS'i.) J. T. [297 

 Electro-magnetic theory of light. — J. W. Gibbs 

 continues his mathematical treatment, obtaining in 

 this paper as tlie general equation of monochromatic 

 light in a medium of any degree of transijarency : — 



^P0t[V]Avc-Vlg]Ave = $ [UUv« + 1- [V ]av., 



where $ and 't' denote linear and vector functions; 

 Pot, the operation by which the potential of a mass 

 is derived from its density; g, the actual potential; U 

 the eli'Ctrical displacement; and p, the period of the 

 luminous disturbance. The symbol [] ..iie denotes a 

 space-avei-age taken through a sphere of unit radius 

 concentric with the point considered. This treatment 

 removes certain objections to the electro-magnetic 

 theory raised by Lorenlz and Kayleigh. The equation, 

 however, is not claimed 1o be rigorously general. — 

 {Amer. journ. sc, Feb., ISSS.) j. T. - [298 



Planetary induction. — M. Quet considers the 

 magnetic induction of the planets on the earth, and 

 obtains 



F _ Ri'VKp / cos^tt — 3;iVi/g — 2/i,A'C0SM-t-4A^ 



where F and I''i represent the forces which Jupiter 

 and the sun, for instance, exert on the earth, Y the 

 volume, N the angular velocity, p the magnetic power, 



u the angle of the magnetic axis with the axis of ro- 

 tation, h and h' the cosines of the angles which these 

 two axes make with the radius vector from the earth's 

 centre. — ( Comptes rendiis, xcv. 23. ) j. T. [299 



Distortion of the spark by statical electricity. 

 — M. Aug. Kiglii argues, that the spark of a disruptive 

 discbarge ought to be acted upon by neighboring 

 statical charges, as if the spark were a body electrified 

 to the same sign as the electrode whose electric dens- 

 ity before discharge is stronger. Experiments in which 

 one electrode of a Iloltz machine is connected with 

 the earth, and also where one electrode has a greater 

 curvature than the other, confirm his conclusions. — 

 {Comptes rendus, xcv. 24.) j. t. [300 



ENGINEERING. 



Regulation of rivers, and prevention of 

 floods. — A valuable report m^on the rectification of 

 the Rhine and Danube has been made by M. Gustave 

 Wex, privy councillor to the emperor of Austria, in 

 whicli an account is given of the work carried on 

 between Mannheim and Basle during the period 

 from 1819 to 1863, by which the distance has been 

 shortened from 2.52 to 169 kilometers, and the fall 

 increased by thirty per cent. The stream has more- 

 over been confined to a uniform channel, the banks 

 being carefully protected, and the old bed with its 

 branches filled, and the land thus reclaimed brought 

 under cultivation. Government considers that the 

 benefits from the change are so large as to make 

 ample payment for the outlay. Similar work upon 

 the Danube has been in progress ^from 1869 to 1881. 

 The author concludes, that from 48 years of observa- 

 tion and experience of extensive works undertaken 

 for the improvement of rivers, it can be confidently 

 stated that by careful study, even the most tortu- 

 ous rivers and the swampiest valleys can within a few 

 years yield the most satisfactory results. — ( Van 

 Nostrand's eng. mag., Feb., 1883.) G. i.. v. [301 



The preservation of timber. — A committee of 

 eight members of the Amer. soc. of civil engineers 

 has made a preliminary report upon the above mat- 

 ter, in which a list of thirty-three different chemical 

 processes is i^resented for preserving wood from 

 decay. The census of 1880 has shown the need of a 

 far more economical use of timber in this country than 

 has prevailed heretofore. Not less than a thousand 

 circulars were sent out to civil engineers, railroad- 

 superintendents, dealers in timber, and chemists; 

 and numerous letters from engineers are given, in 

 regard to the duration of wood under various condi- 

 tions. — {Trans. Amer. soc. civ. eng., Oct., 1882.) 

 G. L. V. [302 



Ne-w harbor at Vera Cruz, Mexico. — The 

 plans of Mr. James B. Eads for a new and extensive 

 artificial harbor at Vera Cruz have been for some 

 time before the engineering world, and the work was 

 commenced last autumn. The natural harbor is ex- 

 posed to gales from the north and north-west, and is 

 often made very danserous during storms. The plan 

 of Capt. Eads provides for a quiet harbor with deep 

 water and suitable lights for guidance of shipping. 

 The cost of the above works is leckoned at about ten 

 millions of dollars. — {Engineering, Nov., 1882.) 

 G. L. V. [303 



CHEMISTRY. 



(.Organic.) 

 Dianilido - phosphorus hydrate. — Professor 

 Jackson mentioned a Dianilido-phosphorus hydrate 

 (Cell, NH) POH, which he and Mr. Menke had 

 obtained by the action of phosphorus trichloride 

 upon aniline. The crude product formed by adding 



