230 



• KNOWLEDGE * 



fAPKir, 20, 1883. 



have reached the " very alarming amount of 800 Ohms." 

 The conductor was jointi^d together by screw couplings, and 

 this extraordinary resistance is explained to have been due 

 to the "defective character of many of those couplings." 

 The resistance of a good conductor should not exceed 

 1 Ohm. 



Thk management of the Savoy Theatre having deter- 

 mined to abolish gas-fittings altogether in the entrance, 

 corridors, and offices, Messrs. Karaday it Son are supplying 

 some tasteful fixtures for the Swan lamps, with which 

 Messrs. Siemen Brothers are replacing them. 



TiiR model theatre of Briinn is illuminated by electricity, 

 and also provided with an electrical safety apparatus, de- 

 vised by Robert Langstoutf Haviland, for use in the event 

 of fire breaking out. By means of an electro-magnet the 

 incombustible curtain between the stage and auditorium 

 is allowed to fall ; the valves of water pipes are opened, 

 so as to discharge copious volumes of water on various 

 parts of the building ; e.xtra doors are opened, and venti- 

 lators are closed. 



Tub experiment of electrically lighting the dining-room 

 and libraries of the House of Commons has, it is stated, 

 cost more than £2,000, but the Commissioner of Works 

 contracted to pay a sum not exceeding £900. 



Professor Palmieri has devised a process for silvering 

 glass by means of the reducing action on the salts of silver, 

 which is said to have the advantage of producing a very 

 brilliant metallic deposit. When into an ammoniacal solu- 

 tion of nitrate of silver is poured, first a little caustic 

 potash, and then a few drops of glycerine, the reduction 

 begins at once ; and this action is accelerated if ether or 

 alcohol be added to the mixture. A moderate heat and 

 darkness are said to increase the brilliancy of the precipi- 

 tate, and darkness also favours the adhesion to the mirror 

 of the deposit. 



The Council of the Society of Arts have appointed a 

 committee to consider the question of preventing colli- 

 sions at sea. The work of the committee will be confined 

 to a consideration of the best means of preventing colli- 

 sions in fogs. The committee will be glad to receive any 

 information on this subject from persons who have given 

 their attention to it, or to consider any proposals having 

 for their object the pn^vcntion of such collisions. All 

 such communications sliould bt; .iddressed to the secretary 

 of the Society of Arts, John-street, Adelphi. 



Mil. John F. Sc;ruLTZ, of New York, has conceived the 

 idea of preventir collisions at sea in a fog, by means of 

 balloons lie proposes that all vessels should be provided 

 with balloons of sufficient capacity to take a person high 

 enough above the fog to see balloons from other vessels that 

 may be in the vicinity. The relative positions of the dif- 

 ferent vessels are then communicated to the captain or 

 other oflicer of the ship, and, by signals between the look- 

 out men in the balloons, the direction of the vessels is so 

 controlled as to avoid collision. The inventor does not 

 state how the man in the balloon is to communicate with 

 the officers of his ship, but it i.^ presumed by an electric 

 wire attached to the cable-line by which the balloon is 

 fastened to the ship's deck. Mr. Schultz does not confine 

 himself to the idea of u.sing balloons on ships alone for pre- 

 venting collisions, but he thinks lighthouses, life-saving 



stations, itc, should be provided with balloons, properly 

 manned, to warn vessels of their approach to land. The 

 inventor of the balloon collision-preventing idea suggests 

 that the present year, 1883, is a most appropriate time for 

 introducing his system, as it miirks an event in ballooning, 

 it being just one hundred years ago that Montgolfier intro- 

 duced his balloon to the world. 



The total number of puddling furnaces in operation at 

 the end of 1882 in the United Kingdom was 4,369, being 

 814 less than in the preceding year. 



During a discussion at the meeting of the Society of 

 Telegraph Engineers, yesterday week, Mr. Stroh said he 

 had been endeavouring to examine microphonic actions 

 with the aid of a microscope. He u.sed platinum electrodes 

 separated by an oily film, aud using only one cell, actually 

 saw the oil boil vigorously and partially volatilise. The 

 telephone and microphone are at present receiving con- 

 siderable attention at the hands of the society, which has 

 devoted the last two meetings to their discussion, and has 

 also allotted the next to the same subject. A new 

 condenser telephone will then, in all probability, be intro- 

 duced. 



The American Bell Telephone Company has, it is said, 

 erected two million miles of overhead wires during the past 

 year. 



Telegraph Wire Struck by Lightning. — The Elec- 

 trician is informed by an eye-witness that : — ''On March 1, 

 near the village of Lacofranco, a flash of lightning struck 

 the line wire about midway between two poles. The 

 current divided and rushed along the wire to either pole, 

 completely destroying the whole of the wire short up to 

 the insulators, where, with a loud report, it jumped to the 

 iron poles and made earth. The length of \^ire dfrstroyed 

 was eighty-five yards. The size of wire was No. 8 B. W.G. 

 galvanised iron. The two ends have a purplish hue, and 

 are like hardened steel. The cups of the insulators (white 

 porcelain) were broken, the upper parts being covered with 

 a purplish, metallic looking coating, radiating from where 

 the line was attacked. The coating is thoroughly burnt 

 into the glaze of the porcelain. The inside of the cups, 

 nearest to where the electric fluid sprang from the line to 

 the iron pole, is covered with a fine, dark, metallic-looking 

 deposit, which is also burnt into the porcelain." 



Petroleum in the Argentine Republic. — Petroleum 

 deposits of great richness and extent are said to have been 

 recently discovered in the upper provinces of the Argen- 

 tine Republic, and it is believed that the eastern slopes of 

 the Sierras of the Andes are underlaid in many places 

 with the oil. One of the deposits, in the province of 

 Jujuy, consists of a lake of about eighty-eight acres in 

 e.xtent, and of unknown depth, and is covered with as- 

 phalte. The liquid itself is somewhat thick, of a black 

 colour, and has no disagreeable odour. It is pronounced 

 equal to the best American petroleum. Deposits of petro- 

 leum have also been recently discovered in the province of 

 Mendoza ; one of these is only a few miles south-west of 

 the old site of the city of Mendoza, destroyed by earth- 

 quake in 1861, and a concession has already been granted 

 by the Government for working these deposits. According 

 to an analysis made in England, excellent results are 

 obtained ; the yield is stated to be nearly 40 per cent, of 

 kerosine, and what adds to the importance of the deposit 

 is the fact that the oil flows to the surface, and thus aflbrds 

 a constant supply of crude petroleum. — Engineering. 



