NATURAL PHILOSOPHY. 123 



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long submarine telegraphs, instead of the battery system heretofore in use. 

 The new apparatus consists merely of a couple of earth plates, positive and 

 negative, one at either extremity of the line, no other battery being used. 

 By such means it is anticipated that all necessity for insulation of the wires, 

 or at least dependence on perfect insulation, will be. obviated, the electricity 

 evolved by a single voltaic couple, while connected with the respective ends of 

 the wire, having no tendenc} T to escape to the earth during transit. The chief 

 difficulty i-elates to the question of intensity, as by the single arrangement 

 increase of surface only affords increase of quality, and not of intensity, as 

 by the battery method. Mr. Beardmore thinks that the present sub-Atlantic 

 cable would prove to be not wholly useless, if efforts were made to work it on 

 his terra-voltaic principle. 



ON THE GREAT AURORAS OF AUGUST AND SEPTEMBER, 1859. 



Professor Loomis, in a paper on the great auroras of August and Septem- 

 ber, 18-39, read before the American Association for I860, characterized the 

 display as unsurpassed by any on record for magnificence and geographical 

 extent. The disturbance of the magnetic instruments was well-nigh unpre- 

 cedented for violence, and it may be safely asserted that the phenomena ex- 

 tended over the entire circuit of the globe. The aurora of September 2d formed 

 a belt of light encircling the northern hemisphere, extending southward in 

 America to latitude 22, and reaching to an unknown distance on the north; 

 until it pervaded an interval between the elevation of fifty and five hundred 

 miles above the earth's surface. The illumination consisted chiefly of lumi- 

 nous beams or columns everywhere parallel to the direction of a magnetic 

 needle freely suspended. These beams were about five hundred miles in 

 length, and their diameter varied from, five to ten or twenty miles, and 

 were, perhaps, sometimes still greater. 



IMPROVED GALYANO-PLASTC PROCESS. 



An improvement in the method of producing copies of busts, statues, 

 groups, and round ornaments, by the galvano-plastic process, has just been 

 made public. The principle of the invention is the use of conductors so 

 arranged as to spread the electrical current over a large surface. The modes 

 of applying it differ according to circumstances. One plan is as follows : A 

 piece of copper, or of charcoal, is made to represent in miniature the form 

 in outline of the object to be reproduced; this miniature conductor is attached 

 to the negative pole, and then introduced into the interior of the mould, 

 which, of course, is in connection with the same pole ; the whole is then 

 plunged together in the bath. The metal is conducted by the various points 

 of this miniature conductor towards all the various hollows which correspond 

 with its prominences. This, however, was but a rude form of the methods 

 adopted. The inventor, M. Lenoir, afterwards substituted for the miniature 

 above described a light frame or mass formed of metallic wire, or of any 

 other conducting material, which he introduced in the same manner into 

 the hollow of the mould; by this means he obtained a large number of 

 conductors, which approached every portion of the interior of the mould, 

 and formed what he calls a mass of nerves for conducting the electricity into 

 the most intricate portions of the hollow mould. These wires also render 

 the decomposition of the solution unusually active, so much so that the 



