On Diseases and Accidents of Fanners. 249 



Danger from Exposure to Cold, — A carelessness with 

 respect to this cause of disease, has often produced se- 



insure its reaching moist earth ; a point of essential importance 

 to insure a speedy dispersion of the electrical fluid. It will not 

 answer to let the end of the rod merely <ouch the top of the 

 ground, nor to let it rest on a rock, even although it should be 

 a foot or two under the surface, because in neither case will the 

 electrical fluid be certainly carried off'. Houses thus pariialh' 

 protected, have been injured by li^^iitning. About tliree jears 

 since a place of worship in Massachusetts was struck, that had 

 a conductor just touching the ground, and Mr. Thomas Leiper's 

 house at Crum Creek was shattered, several years since, not- 

 withstanding he had two conductors to the house, both of which 

 rested on rocks a few feet under ground. 



4. The lower end of the rod ought to be coated with a paste 

 of black lead,* to prevent rust, and also be surrounded by a 

 bushel or two, if possible, of charcoal, coarsely pounded and 

 moistened. 



5. There must be two conductors to a building when it is 

 more than 40 feet long ; one at each end, and these ought to be 

 firmly connected by a rod, or strip of lead, lying on the roof; 

 because the quantity of electrical fluid in the cloud passing over 

 one end of a building, aiay be greater than the rod there can car- 

 ry off*; and hence the redundant portion will spend its force on 

 the house; whereas, if there are two rods connected, the light- 

 ning will be divided between them, and the house be saved. 

 Besides, if there be only one rod, the charged cloud may pass 

 over that end of a long building to which no rod is attached, 

 and there cause havoc; such cases have happened. The house 

 at Purfleet was struck, although a rod was attached to the ridge, 

 only 46 feet distant from the corner where the lightning spent 

 its force ; and a few years since, near Philadelphia, one end of 

 a tanner's frame bark house, 70 feet long, and having a rod at 

 the other end, was also struck and the house consumed. 



6. Additional security would be obtained by having the water- 

 spouts made of copper, and by fornnng a communication between 

 them and the rods, carrying an iron or copper rod from the 

 lower end of the spouts to moist earth, or into water. 



* This may be done by powdering ihe bl^ck lead, mixms it with melted sul[)hur, 

 and then applying it to the rod wliile hot, as recommended by Mr. U. Patterson, 

 late President of the American Philosophical Society. 



