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SCIENCE. 



THE PARIS ELECTRICAL EXHIBITION. 



[From Our Paris Correspondent.! 



To the Editor of " SCIENCE." 



This letter leaves Paris somewhat late, considering the 

 official opening of the Electrical Exhibition took place 

 eight days ago, and that the opening to the public fol- 

 lowed the next day, viz., the nth of August, but in fact 

 the exhibition is not opened even yet, although the pub- 

 lic is admitted during some'hours of the day to look at 

 the half-finished structures and to inspect the dust-cov- 

 ered instruments. 



The daily newspapers and some so-called scientific 

 papers, which give to their readers sensational articles 

 rather than correct information, have been for about ten 

 days crowded with descriptions of the opening and the pro- 

 gress of the electrical exhibition, but the real good scien- 

 tific papers have hitherto only given short notes, because 

 it has, as yet, been impossible to study the value of the 

 different instruments in the exhibition building, where 

 everything is still in a half-finished state and where the 

 noise of hammers and carpenters' instruments are still 

 heard in every corner. 



Notwithstanding this, I will endeavor to give you in 

 this letter a description of the actual state of the exhibi- 

 tion, which will serve your readers as an introduction to 

 the more special articles with which I will furnish your 

 paper weekly. 



When we first enter the Palais de '/Industrie through 

 the principal pavilion, which is situated on the side of the 

 Champs Elysees, we observe a series of beautiful statues 

 which serve as "candelabres" for lamps of theWerdermann 

 system, and when we approach the entrance to the great 

 nave our eyes are attracted with two enormous images 

 representing a male and female lion, while we observe 

 above our head a beautiful chandelier of iron wrought in 

 tastelul style, furnished with Siemens lamps. This 

 lustre will undoubtedly be very attractive if the arrange- 

 ments for the light are made as carefully by the French 

 firm of the well-known house of Siemens, as those in the 

 German department, where some evenings ago the pre- 

 liminary experiments made with the Siemens lamps 

 attracted the general admiration of all those who had 

 the privilege to witness them. 



In the centre of the nave a light-house is erected, 

 which is a copy of the light-houses that guard the 

 coasts of France. It is surrounded by a small 

 water-basin, which, although it may be called orna- 

 mental, is perfectly useless for the purpose for which 

 it is destined, on account of its limited dimensions 

 and the outlines of its borders, which form a star. This 

 basin is intended as a field of exercise for the boat of M. 

 Trouve, called the Telephon, which is driven by an 

 electric motor, in connection with a Bunsen battery, and 

 the length of which nearly equals the radius of the cir- 

 cumference of the basin. 



I may here say a few words about M. Trouve's boat, 

 on account of which a good deal of nonsense has been 

 published in European and American papers, one of the 

 latter mentioning not long ago that M. Trouve's boat, 

 with which he experimented upon the Seine, contained 

 a battery of M. Faure, but M. Trouve is too well ac- 

 quainted with the value of scientific instruments to 

 depreciate the merits of the Plante battery and to substi- 

 tute for it Faure's modification, as long as the former 

 is better. 



Count Du Moncel, whose name is well known among 

 all electricians, on account of his excellent work on the 

 " Application of Electricity," which is the most complete 

 work of its kind in existence, and also on account of his 

 other numerous publications and inventions relating to 

 this part of Science, presented on the 7th of July last a 

 note to the Academy of Sciences, in which M. Trouve 

 describes in a very precise manner the motor used by 



him in propelling a little boat. This note will give to 

 your readers exact and correct information regarding the 

 merits and properties of the motor used in the little canoe 

 which is now seen in the Electrical Exhibition, and I 

 therefore quote this note verbatim : 



" A motor having a weight of 5 kilogrammes and in 

 connection with six elements of a secondary battery of 

 Plante, which produces a labor of 7 kilogrammeters per 

 second, was placed on the 8th of last April upon a tricy- 

 cle, which latter, rider and battery included, had a weight 

 of 160 kilogrammes, and gave to the vehicle a celerity of 

 12 kilometers per hour." 



" The same motor, used on the 26th of May, in a boat 

 having a length of 5.50 meters and a breadth of 1.20 

 meters, holding three persons, gave to this boat a celerity 

 of 2.50 meters in descending the Seine at Pont-Royale 

 and of 1.50 meter in moving against the current. The 

 motor obtained its electro-motive power by means of two 

 batteries, consisting each of 6 elements of bichromate of 

 potash, and the propeller was furnished with a coil hav- 

 ing 3 branches. 



" On the 26th of June I renewed the experiment upon 

 the quiet waters of the upper lake of the Bois de Bologne, 

 using a coil with 4 branches having diameters of 0.28 

 meter and being in connection with 12 elements of Bun- 

 sen with flat plates such as are used in the Ruhmkorff 

 battery. The liquid of these elements consisted of one 

 part of hydrochloric-acid, one part of nitric acid, and two 

 parts of water in the porous vessel, in order to diminish 

 the disengagement of hypoazotic vapors. 



" The celerity of the little boat, which was measured 

 with an ordinary log, rose in the commencement to 150 

 meters within 48 seconds, or a little more than 3 meters 

 per second ; but after three hours of working it had 

 diminished to 150 meters during 55 seconds. After five 

 hours of working the electricity was still 2.30 meters per 

 second." 



So much about M. Trouve's boat, of which a number 

 of miniature specimens, in good working order, may be 

 seen in the upper story of the Exposition building. 



At the left-hand side of the nave, nearest to the light- 

 house, are the exhibitions of Great Britain, Germany and 

 the United States. The exhibition of Germany is that 

 which has the most imposing appearance and is also that 

 which was first completed. Two enormous " candela- 

 bres " in forged iron ornament the entrance of the 

 department, and contain lamps of " Gebrueder Siemens " 

 of Berlin. Near them stand two trophies crowned with 

 the Prussian eagle, and behind them, upon a large num- 

 ber of tables, may be seen a collection of electrical instru- 

 ments of all kinds, which we will describe in our reports 

 hereafter. At the right-hand side of the department we 

 see the busts of five German pioneers in the field of Elec- 

 trical Science, viz.: Otto von Guericke, Ohm, Sdmmer- 

 ing, Steinheil, and Gauss. 



The historical collection of instruments in the German 

 department is of the highest interest in a retrospective 

 way. I will only mention an exact copy of the first 

 machine for static electricity, constructed in the year 

 1670 by Otto von Guericke, consisting of a sulphur globe, 

 which was electrified by turning it by means of an axis 

 and using the hand as a rubber ; an electrical egg, so- 

 called, property of Prince Pless, of Germany, and con- 

 structed at the commencement of the 1 8th century; an 

 electro-chemical apparatus for telegraphing, constructed 

 by Thomas Sommering in Munich in the year 1809 — 

 the telegraphing with this instrument is done by the 

 decomposition of water. A magneto-electric telegraph 

 of Gauss and Weber, constructed in 1833 — this telegraph 

 was used in 1837 in order to keep up a telegraphic com- 

 munication between the physical laboratory aud the mag- 

 netical observatory in the University of Gottingen ; the 

 copy of the first telephone ever constructed, and invented 

 in the year 1861 by Reis, and a great many other appa- 

 ratus of equal interest. 



