SCIENCE LETTER FROM PARIS, 547 



of di Vinci's screw-propeller exist in the National Library of Paris, as also those 

 of his machines for aerial navigation. 



The Congress of electricians in its twenty days sittings, has done good work 

 by adopting unity of views and correlating common results. Science will gain 

 the first by this homogeneity, and next the public. It has unified the standard 

 of electric measures, so as to express in a uniform manner, and according to the 

 decimal system, the force, the intensity or volume, and the resistance of an 

 ■electric current. M. Denayrouse made a warm appeal to the partisans of elec- 

 tricity to unite to secure the full benefits of electric discoveries. The obstacles 

 to the practical extension of these benefits, are statesmen and municipal councils, 

 aided by no less than twenty different inventors, each claiming the pre-eminence 

 for his own system. Were these social impediments conquered, there would be 

 no difficulty in transmitting electric energy like gas, and transform it into light 

 and mechanical power, and so enable workmen to toil, not in a factory, but in 

 the bosom of his family. M. Siemens executed a most brilliant experiment; he 

 arranged a crucible in a certain position, placed therein fragments of steel, plac- 

 ing over same the perforated cover; the two currents furnished by an electro- 

 motor wired, one at the top the other at the underneath, part of the crucible ; in 

 fourteen minutes the mass of steel became red hot and melted, and the quantity 

 of fuel expended to work the electro-generator was less than what would be nec- 

 essary to secure fusion by the direct application of heat. The mass of metal as 

 melted by M. Siemens, presented no blisters. 



Attention remains unabated relative to the subjects of electric domestic 

 lamps,, and I might add, domestic and portable electric motors ; the latter appears 

 to be but a question of cost, the former but of choice. The Maxim lamp has un- 

 doubtedly become a favorite with the public; it is economical and moderateur ; 

 its light is intense, yet as soft and as supportable as that of gas, while possessing 

 more regularity and fixedness. Mr. Maxim's generating machine by the length 

 of one horizontal ring, enables mixed illumination to be obtained, that is, to 

 utilize the variety of the current for the incandescence and the other for the 

 voltaic arc. The Weston generating machine also deserves praise for the excel- 

 lent uniformity with which it generates electric currents for lighting purposes. 

 At the Grand Opera the government instituted a series of experiments to test the 

 several systems of illumination versus gas; the arrangements were incomplete, so 

 the result is undecided. It was at two of these experimental representations 

 Ihat the Maxim lamp won so many honors. 



