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TRANSACTIONS OF THE SECTIONS. 35 
pet yields a good supply of electricity. The effect of the increased thickness is 
obviously to improve the insulation of the carpet. The carpet must be quite dry, 
and also the floor of the room, so that the fluid may not be conveyed away as soon 
as it is excited. These conditions will not generally exist except in winter, and in 
roonis which are habitually kept quite warm. The most remarkable cases which I 
have heard of in New York have been in close, well-built houses, kept very warm 
by furnaces. These furnaces are erected in the cellar and are filled with anthracite 
coal, which is kept constantly burning from autumn till spring. The heated air is 
conveyed to the hall, the parlours, and to every room in the house, as far as is desired, 
through large flues built in the walls, the flues having a section of about one square 
foot. In such a house the wood during winter becomes very dry, and all the furni- 
ture shrinks and cracks, The electricity is most abundant in very cold weather. In 
warm weather only feeble signs of electricity are obtained. The rubber, viz. the 
shoe, must also be dry like the carpet, and it must be rubbed upon the carpet some- 
what vigorously. By skipping once or twice across a room with a shuffling motion 
of the feet a person becomes highly charged; and then upon bringing the knuckle 
near to any metallic body, particularly if it have good communication with the earth, 
a bright spark passes. In almost any room which is furnished with a thick woollen 
carpet, and is kept tolerably warm and dry, a spark may thus be obtained in winter; 
but in some rooms the insulation is so good, and the carpets are so electrical, that it 
is impossible to walk across the floor without exciting sufficient electricity to give a 
spark, It may be thought that in walking across a room there is but little friction 
between the shoe and carpet, but it should be remembered that the rubber is applied 
to the carpet with uncommon force, being aided by the entire weight of the body, so 
that a slight shuffling motion of the feet acts with great energy, 
Account of an instance of Converging Rays seen at Greenisland, on the 
Antrim Shore of Belfast Lough, August 13, 1857. By J. J. Mureny. 
At about 6 p.m., after a thunder-storm—which was the second on that day—a 
rainbow was formed. The phenomenon to be described was seen about the left-hand 
part of the rainbow. The sky outside the rainbow was of that purple black which 
accompanies thunder-storms. Inside it was lighter, and diversified by alternate dark 
and bright rays, like those of an aurora, which appeared to converge to a point a 
little above the centre of the rainbow, but below the horizon. These rays fluctuated 
__ like those of an aurora, but much less rapidly, their changes being scarcely quick 
_ enough to be visible. The dark rays extended through the rainbow, almost blotting 
it out where they crossed it. The rays were continued outside the rainbow at the 
period of their greatest intensity, but not all the time, and were never so distinct 
outside as inside. The dark rays were of the same purple black colour as the sky - 
outside the rainbow ; the light rays were like what we call “‘ watery sunshine.” This 
appearance lasted in all about three-quarters of an hour. The light rays began to 
_ disappear one by one from the horizon upward,—the dark ones being welded toge- 
_ ther into a mass of purple darkness, which, as it ascended, blotted out the rainbow. 
- In this way the lower part of the rainbow and the rays disappeared. The upper 
_ part of both disappeared by vanishing, the rays being tlie iast completely to disap- 
_pear. After this, there was some thunder and much rain. ‘Another rainbow was 
_ formed during the evening which did not contain any rays, but resembled the former 
‘in having a dark sky outside and a light one inside. 
Examination of some Problems of Meteorology. New and complete Explana- 
4 tion of the Rainbow. By M..’AzBé RAILLARD. 
__ The principal object which I present today, is a new and complete explanation of 
_therainbow. I show that the efficient rays of Descartes never enter into the formation 
of this phenomenon, but that it is always and solely produced by interferences. I 
_ apply to the rainbow the principle of interferences, not only as Dr. Young has done 
it, in his explanations of the supernumerary bows, but according to the much more 
exact and complete views of Mr. Airy. Dr. Young preserves in fact to the primary 
al 3% 
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