94 . KANSAS CITY REVIEW OF SCIENCE, 



CORRESPONDENCE. 



SCIENCE LETTER FROM PARIS. 



Paris, April 3, 1882. 



The Chemin de fer du Nord, has been since some time occupied to discover 

 an electric lamp for its locomotives, capable of lighting the line some 330 yards 

 ahead. The difficulty to surmount consisted to find a lamp that would not be- 

 come extinguished by the continued trepidations of the engine. The fixity of 

 the electric light depends upon the uniformly maintained distance between the two 

 sticks of carbon, in the middle of which flashes the electric arc. Now the jerky 

 motion of the locomotive tends to break this arc. Messrs. Sedloczek & Wiku- 

 lith have combined a very simple lamp, suited to the special necessity in ques- 

 tion. The mechanism is briefly this : Two parallel vertical tubes, of unequal 

 diameter, united below by a horizontal tube in the form of a U; in the tubes, 

 glycerine, and above, floating on the liquid, a piston ; each piston has a stem, 

 from each stem branches a splint of carbon, one above the other, but in the 

 same vertical hne. It follows as a matter of course, that any shock which pushes 

 up one of the pistons acts similarly on the other, so that the space between the 

 carbon sticks is maintained, the glycerine also tends to deaden the trepidations. 

 A cock placed in the horizontal tube, that opens or shuts by the electric current, 

 keeps the pistons and their carbon points in their respective positions, pending 

 the combustion. 



The lamp has been satisfactorily tested ; it is fed by a Schuchert dynamo- 

 electric machine installed on the platform of the engine, the current being gener- 

 ated by a Brotherhood motor of three cylinders, representing a three-horse pow- 

 er. When the locomotive was running at forty-five miles an hour, the light 

 remained steady, and lit up objects 500 yards ahead, and the line guards were 

 able to discern objects at a distance of 880 yards ; the light did not affect the 

 distinctive colors of the signals, nor were the drivers of the engine when cross- 

 ing, dazzled by excess of light. The results of the experiments justify the adop- 

 tion of electricity for the reflecting lamp of locomotives, suspended at a height 

 of fifteen feet. 



In the elevated regions of the Cordilleras, doctors and travellers have drawn 

 attention to the accidents resulting from asphyxia, to which newly arrived Euro- 

 peans are exposed. Even domestic animals do not escape. The Indians and 

 wild animals occupying the high points, are exempt from the dangers of the rare- 

 fied air, but the inhabitants of the plains faint away from the repeated muscular 

 efforts to breathe. It is a disease not unlike "Mountain Sickness" in Europe, 



