Chap. 6.] Conducing Rod*. 35* 



through bodies, produce heat iti them, provided they 

 are proportionally fmall. Thus, in pafllng through 

 the fmall wire, the particles are confined to a narrower 

 paflage, and, crowding clofe together, act with a more 

 condenied force, and produce fenfible heat * 



The difcovery of Dr. Franklin, which eftablifhed 

 the identity of lightning with the electrical fluid, fug- 

 gefted an invention, for which we are indebted to the 

 fame philofopher, for fecuring buildings from this moft 

 formidable enemy. The reader will perceive that I 

 allude to that of metallic conductors. 



Suppofe Fig. 4. Plate XXVI. to reprefentthe gable 

 end of a houfe, fixed vertically on the horizontal board 

 F G ; a fquare hole is made in the gable end at b i 9 into 

 which a piece of wood is fixed ; a wire is inferted in 

 the diagonal of this little piece j two wires are alfo 

 fitted to the gable end ; the lower end of one wire 

 terminating at the upper corner of the fquare hole, 

 the top of the other wire is fixed to its lower corner; 

 the brafs ball on the wire may be taken off, in order 

 that the pointed end may be occafionally expofed to 

 receive the explofion. 



Experiment. Place a jar with its knob in contact 

 with the conductor, connect the bottom of the jar 

 with the hook H, then charge the jar, and bring the 

 ball under the conductor, and the jar will be dif- 

 charged by an explofion from the conductor to the 

 ball of the houfe. The wires and chain being all in 

 connection, the fire will be conveyed to the outfide of 

 the jar without affecting the houfe ; but if the fquare 

 piece of wood Is pLiced (b that the wires are not con- 

 nected, but the communication cut off, the electric 

 fluid, in pafllng to the outfide of the bottle, will throw 



* Pneftley^ Hilt, of Elecl. p. 394. 



out 



