^36 Exfir'imcnt v;ith an Artificial Tf.'unJef'ClouJ. 



EXPERIMENT. 



THAT this experiment might refemble, as much as an eleclrical apparatus is capable of 

 exhibiting, the operations of nature, it was performed by charging and difdiarging plates 

 of air. 



Arrar.giinent of the Apparatiij. 



THE metallic chains affixed to the interior tinfoiled cylinders are connefted with the tin- 

 foiled boards which reft upon the floor of the room. A metallic communication is then 

 made between thefc boards, and another metallic communication between the exterior cy- 

 linders, which remain infulatcd. 



The exterior cylinders, thus united, are conne£led with one of the conduflors of the elec- 

 trical machine (in this experiment it is with the poCtive); the other condudlor (or rubber) 

 being conne£led with the earth. 



The ele£lrical machine being put in a£lion, the exterior tinfoiled cylinders become eledlri- 

 fied i and, the interior cylinders being eonneded with the earth, the body of air between 

 them becomes charged ; and, if a circuit be made between the exterior and interior cylin- 

 ders, an explofion takes place, and a ftrong eleftrical fliock may be felt. 



The exterior cylinders reprefent the upper furface, and the interior cylinders reprefent the 

 lower furface of a body, of charged air in the atmofphere. 



The moveable body, reprefcnting a cloud moving in the air, is connected with the exte- 

 rior cylinders, by which means it becomes a part of the upper eleflrified furface of the body 

 of charged air, and can be made to pafs over the building at pleafure. 



One of the metallic rods, placed in perfedl communication with the earth (but feparatc 

 from the communication of the interior cylinders with the earth), reprefents a metallic con- 

 du£lor attached to a building. 



The infulated metallic balls, with the rofin placed in the interval between them, are fup- 

 pofed to reprefent any metallic fubftances belonging to the building. 



A glafs tube filled with water, and about i8 inches in length, is placed between the con- 

 ductor and one of thefe balls, to reprefent a conducing communication, which muft fre- 

 quently occur during a thunder-ftofm, between the conduiSlor and other metallic fubftances 

 belonging to the building. 



Since a conductor may be raifed to any height at pleafure, it is, in this experiment, fup- 

 pofed to be raifed rather beyond the diftance at which any pointed metallic fubftances be- 

 longing to the building might, by their influence on the operations of tlie eleclrical fluid, 

 endanger the building. 



This experiment may be divided into three cafes, ift, The eleflricity oppofitc to that 

 of the cloud may extend over the conduftor, and all other metallic fubftances belonging to 

 the building, jdly, it may extend over fonie metallic fubftances, but not over the conduc- 

 tor, jdly. It may not extend over the coaduclor, or over any part of the building. 



CASE 



