458 PHILOSOPHICAL TRANSACTIONS. [aNNO IJSl. 



about 1 feet 1 inches diameter ; this he suspended by a hair-line on a nail, 

 driven into a beam : the line was about 4 feet long : then the leaf-brass being 

 laid under the hoop, the tube was rubbed, and held within the hoop, near its 

 upper side, without touching it, by several inches : then the lower part of the 

 hoop attracted and repelled the leaf-brass strongly ; but when held near the 

 lower part, there was very little, if any attraction. If the tube were held near 

 the outside of the hoop, it attracted ; but strongest, when at the same time it 

 was held near the knot of the hair-line, by which the hoop was suspended. To 

 this hoop there was tied a less hoop of about a foot and a half in diameter : it 

 was tied to it by packthread; so as to hang below it about 1 inches. They were 

 suspended together by the hair-line ; then the leaf-brass and tube being pre- 

 pared, as beforementioned, the tube being held near the upper hoop, the lower 

 part of the lower hoop attracted strongly ; and when held near the upper part 

 of the lower hoop, but very weakly : but when held near the lower part of the 

 lower hoop, there was no attraction. 



September 5, Mr. Gray made the following experiment ; which shows that 

 the electric effluvia have the same eftect in a circle, when its position is hori- 

 zontal. He took a large hoop, of somewhat more than 3 feet diameter, and 

 about 1\ inches in breadth : to this were tied, at nearly equal distances, 4 lines 

 of twine (i.e. 3 threads of packthread twisted together) each about 1 feet 8 

 inches long. These were tied with their ends together to a hair-line of about 

 1 feet and a half long, by which the hoop was suspended on a nail, as in the 

 other experiments ; so that the hoop hung now in a horizontal position. Then 

 the brass-leaf being laid under the edge of the hoop, at between 2 and 3 inches 

 below it, the tube being rubbed, and held between the cords without touching 

 them, the leaf-brass was attracted and repelled for several times together ; but 

 when held near the outside of the hoop, opposite to that part where the leaf- 

 brass lay, the attraction was much stronger. 



About the latter end of autumn 1729, he resumed his inquiry after other 

 electric bodies, and found many more that have the same property, and may be 

 excited to attract by the same method. As for instance, the dry withered leaves 

 of reeds and flags, grass and corn, both leaves and straw ; the leaves of trees, 

 as those of the laurel, oak, walnut, chesnut, hazle nut, apple and pear-tree 

 leaves : so that it may be concluded, that the leaves of all vegetables have this 

 attractive virtue. 



Mr. Gray made the following experiments at his chamber, March '23, 1730. 

 — He dissolved soap in the Thames water ; then he suspended a tobacco-pipe 

 by a hair-line, so as that it hung nearly horizontal, with tiie mouth of the bowl 

 downwards ; then having dipped it in the goap-liquor, and blown a bubble, the 



