-1859] WRITINGS OF JOSEPH HENRY. 373 



conductor than the wood is to attribute to this agent pre- 

 science and forethought, but by an application of the prin- 

 ciples of induction, the whole is referred to the simple action 

 of attraction and repulsion. In the interior of a house the 

 safest position we can well imagine is that of being horizon- 

 tally suspended in a hammock by silk cords in the middle 

 of a room, and perhaps the next, that of lying on a mattress 

 or feather bed on a wooden bedstead the materials of which 

 are very imperfect conductors. It is scarcely necessary to 

 say that if the bedstead be in the middle of the room, at a 

 distance from the wall, the danger will be still less. 



It may perhaps be well to dwell for a moment on the ex- 

 planation of the foregoing statement. Let us suppose a man 

 to be standing on a large piece of bees-wax, which is almost 

 a perfect non-conductor, and exposed to a cloud highly 

 charged with positive electricity. A portion of the natural 

 electricity of his head would be drawn down into his feet; 

 the former would become negatively electrified and attract 

 the lightning of the cloud, while the latter would repel it; 

 the tendency to be struck would be on account of the dif- 

 ference of these two actions. If the man stepped off the non- 

 conducting wax on to the earth the redundant electricity 

 which had collected in his feet would be discharged, his 

 head would become still more negatively electrified, the re- 

 pulsion which existed in the other case would disappear, 

 while the attraction weuld be increased, and hence the ten- 

 dency to be struck would be much greater. 



Let us next consider what would take place if a man 

 should be extended horizontally on a large disc of beeswax. 

 In this case the upper part of the body, or that toward the 

 sky, would become negative, and the lower part, or that in 

 contact with the beeswax, would become positive, and the 

 attractions and repulsions would be exhibited as in the first 

 instance, but with less energy, because their foci would be 

 much nearer each other, and consequently they would act 

 with almost equal effect ; while the repelled electricity not 

 having space into which to descend, a less quantity of it 

 would be repelled from each point of the upper surface. If 



