332 Sir C. Wheatstone on Error in Electroscopy . [Apr. 28, 



electricity becomes free and expands itself in the body. A single stamp on 

 the carpet followed by an immediate removal of the foot causes the index of 

 the electrometer to advance several degrees, and by a reiteration of such 

 stamps the index advances 30° or 40°. 



The opposite electrical states of the carpet and the sole of the boot were 

 thus shown : after rubbing, I removed the boot from the carpet, and placed 

 on the latter a proof-plate (i. e. a small disk of metal with an insulating 

 handle), and then transferred it to the plate of the electrometer; strong 

 positive electricity was manifested. Performing the same operation with 

 the sole of the boot a very small charge was carried, by reason of its ready 

 escape into the body. 



The negative charge assumed by sole-leather when rubbed with animal 

 hair was thus rendered evident. I placed on the plate of the electrometer 

 a disk of sole-leather and brushed it lightly with a thick camel' s-hair pen- 

 cil ; a negative charge was communicated to the electrometer, which charge 

 was principally one of conduction, on account of the very imperfect insu- 

 lating power of the leather. 



Various materials, as India-rubber, gutta percha, &c, were substituted 

 for the sole of the boot ; metal plates were also tried ; all communicated 

 negative electricity to the body. Woollen stockings are a great impedi- 

 ment to the transmission of electricity from the boot ; when these experi- 

 ments were made I wore cotton ones. 



When I substituted for the electrometer a long wire galvanometer, such 

 as is usually employed in physiological experiments, the needle was made 

 to advance several degrees. 



At the Meeting of the British Association at Dublin in 1857, Professor 

 Loomis, of New York, attracted great attention by his account of some re- 

 markable electrical phenomena observed in certain houses in that city. It 

 appears that in unusually cold and dry winters, in rooms provided with 

 thick carpets and heated by stoves or hot-air apparatus to 70°, electrical 

 phenomena of great intensity are sometimes produced. A lady walking 

 along a carpeted floor drew a spark one quarter of an inch in length be- 

 tween two metal balls, one attached to a gas-pipe, the other touched by her 

 hand ; she also fired ether, ignited a gaslight, charged a Leyden jar, and 

 repelled and attracted pith-balls similarly or dissimilarly electrified. Some 

 of these statements were received with great incredulity at the time both 

 here and abroad, but they have since been abundantly confirmed by the 

 Professor himself and by others. (See Silliman's American Journal of 

 Science, July 1858.) 



My experiments show that these phenomena are exceptional only in de- 

 gree. The striking effects observed by Professor Loomis were feeble 

 unless the thermometer was below the freezing-point, and most energetic 

 when near zero, the thermometer in the room standing at 70°. Those 

 observed by myself succeed in almost any weather, when all the necessary 

 conditions are fulfilled. Some of these conditions must frequently be 



