548 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



the Cooper Union, and applied it years ago to the ignition of com- 

 mon coal gas. 



3. The platina wire heated by a galvanic current, is often used 

 in experimenting to ignite all kinds of vapors, gas, lamps and can- 

 dles. I have still an old apparatus made for this purpose, and 

 applied it practically (however on a small scale,) in my lecture 

 on physics in 1842. It is also extensively used for igniting gun- 

 powder in blasting rocks, as the easiest way to reach them if they 

 are under water ; it has been done in the harbor of New York, 

 and in Hurlgate, by Maillefert. However this method was never 

 applied on a large scale for lighting gas till some years ago Gard- 

 ner obtained a patent in this country to light many gasburners in 

 the same time, by platina wire, heated by a powerful galvanic 

 battery. 



4. It is a common experiment at present, that the rubbing of 

 the feet on the carpet in a very dry room, will produce electricity' 

 enough, and charge the person with it, so that by touching the 

 gas burner Avith his finger the experimenter may produce a small 

 spark, which will ignite the gas. 



5. As such a small spark is sufficient to ignite inflammable 

 gases, it is clear that with a powerful apparatus we may pro- 

 duce 100 sparks at the same time, at the jets of several hundred 

 gas burners, so with a galvano-electric induction apparatus, in- 

 vented by Rumhkorf, in Paris, (the most powerful electric ma- 

 chine yet known,) we may light several hundred burners if we 

 connect them all with metallic wire in such a way as to produce 

 a spark at each gas jet. It is for this application of electricity 

 that Mr. Wilson obtained a patent ; it is applied at the Cooper 

 Institute, where the 300 gas burners in the large hall in the base- 

 ment are lighted by sparks obtained from a Rumhkorf induction 

 coil, conveyed from my laboratory, five stories above, along iso- 

 lated wires partially hidden in the walls of the building, over a 

 distance of about 1,000 feet. This Rumhkorf apparatus is based 

 on the same principle as the well known galvanic-electric or so 

 called shocking batteries, in use for medical purposes during 

 many years, and for every slight modification of which several 

 patents have been taken out. The most important modifications, 

 however, are those applied by Rumhkorf to the machine bearing 



. his name. This is of course not patented, but belongs to the sci- 

 entific world, and perhaps is nowhere better made than by Ritchie, 

 in Boston, who manufactured the apparatus of this Institute. 



