VOL. XXXIX.] rHILOSOPHICAL TRANSACTIONS. 3 



caused the cock to be stripped of all his feathers ; and the difference was still 

 not very considerable. 



They took a large surloin of beef, and suspended it on the silk-lines : then, 

 on holding the fingers near any part of it, there was a snapping, and the fingers 

 were pushed or pricked : but the snapping was thought not to be quite so loud, 

 as when the experiment was made on the cock. 



They caused to be made an iron rod, 4 feet long, and about half an inch 

 diameter, blunt pointed at each end. This was suspended on the lines : then 

 the tube being rubbed, and held near one end of the rod ; and then the finger 

 or cheek being put near either end of it, the effect was the same as when 

 an animal was suspended on the line, with respect to the pricking pain. 



At night they made the luminous part of the experiment ; suspending the 

 iron rod on the silk lines ; then applying one end of the tube to one end of the 

 rod, not only that end had a light on it ; but there proceeded a light at the same 

 time from the other end, in form of a cone, the vertex being at the end of the 

 rod ; and it plainly consisted of rays of light, diverging from the point of 

 the rod ; and the exterior rays incurvated. This light is attended with a small 

 hissing noise ; and every stroke given to the tube, causes the light to appear. 

 The hissing seems to begin at that end of the rod next the tube ; and as it 

 comes, increases in loudness ; but it is so small as not to be heard without good 

 attention, and by those only that stand at the end of the rod from whence the 

 said light proceeds. 



Mr. Gray repeated the experiments, by laying a rod of iron on a cake of 

 shell-lac, which was laid on a glass-vessel : and the effects were much the same 

 as mentioned above. 



Having caused to be made 3 iron rods, one 4 feet long, and two 3 feet long 

 each ; one of these was made tapering towards the ends, and pointed as that of 

 4 feet was ; the other pointed at one end, and the other end not pointed, the 

 diameter of the rods about half an inch ; they were first forged, then filed and 

 burnished. With these Mr. Gray made the following experiments : when any 

 of them were laid on the brims of hollow cylinders of glass well warmed, or 

 on cakes of rosin and bees-wax, or on those of sulphur, the phenomenon was 

 the same, as when they had been suspended on silk lines. But now he dis^ 

 covered a very surprising one, viz. that after the tube had been applied, and the 

 light seen at both ends, on going to the other end of the rod, when there was 

 no light to be seen, and holding his hand at some distance from it, then moving 

 his hand towards it with a pretty swift motion, there issued from that point of 

 the rod a cone of light, as when the tube had been applied to the end : and on 

 repeating this motion of his hand, the same phenomenon appeared for 5 or 6 



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