1841] WRITINGS OF JOSEPH HENRY. 199 



a shock in the knees and lower joints of the legs. The wife 

 stated that the feeling was precisely like that which she had 

 experienced from a shock from an electrical jar. No marks 

 of the entrance of any part of the discharge from the cloud 

 were found on the plastering or any other parts of the room; 

 the effect can therefore only be accounted for by a sudden 

 disturbance of the equilibrium of the natural electricity of 

 the space within the room. 



The induction of an electrical cloud is often exerted at an 

 astonishing distance. It has long been known that a deli- 

 cate gold-leaf electrometer is sometimes affected by the pres- 

 ence of an electrical cloud immediately overhead ; but Dr. 

 Ellet, professor of chemistry' in the college of South Carolina, 

 has informed him that if one of Dr. Hare's single-leaf elec- 

 trometers be furnished with a pointed metal rod attached to 

 the cap, and then placed on the sill of an open window in 

 the upper story, the leaf will be seen to touch the ball at the 

 moment of a flash, although the lightning is several miles 

 distant. 



