460 Mr. Pattmson*s further Experiments on the 



iron bar, placed upright in a cask of rosin (both to insulate it 

 and to serve as a Foot), and a horizontal arm projecting from 

 it, made to slide up and clown on the vertical bar, the large 

 conductor could be placed in any part of the cloud of steam 

 issuing from the valve, and the electricity given off could be 

 conveyed from it in any direction. Care was taken to round 

 off all parts of this conductor, so as to avoid sharp points and 

 angles as much as possible. On trying this large conductor in 

 the current of steam from the Wellington, we were disap- 

 pointed to find that it did not yield a longer spark than the 

 small pointed copper rod with which we had previously ex- 

 perimented. The spark was larger in volume, but it did not 

 possess greater intensity. It never struck through more than 

 three inches of space, but its effect upon the person when 

 taken was very violent and painful. Our intention was to 

 have ascertained the rate at which large jars could be charged 

 from the steam, in order to form some idea of the quantity of 

 electricity given off; but the evening had become very damp, 

 and the air was so moist, that we could not procure sufficient 

 insulation, and were obliged to relinquish the attempt. 



7. When the large conductor was held in the cloud of 

 steam with its lower part or apex about two feet above the 

 valve, it gave off numerous and powerful sparks ; but if at 

 this time the points of the small conductor were placed by 

 a person connected with the ground in the steam below 

 the large conductor a foot above the valve, the electricity 

 given off by the large conductor was very materially dimi- 

 nished. 



8. By means of screws, the entire engine (the Wellington) 

 was raised off" the rails and placed upon blocks of baked wood, 

 so as to insulate it entirely. The steam being now blown off 

 at the valve, the boiler and engine became strongly electrical 

 with negative electricity ; points placed upon any part of the 

 engine exhibiting the peculiar star of the negative element, 

 and threads suspended from the engine being repelled by ex- 

 cited sealing-wax. The steam was at the same time strongly 

 positive, and when a point connected with the conductor held 

 in the steam was brought near a point attached to the insu- 

 lated boiler, the pencil upon the former and star upon the 

 latter were beautifully decisive as to the electrical states of 

 each. 



9. I repeated Volta's experiment by placing a hot cinder 

 upon the cap of a gold-leaf electrometer, and projecting a few 

 drops of water upon it, when the leaves diverged strongly 

 with negative electricity. I observed, that when the cinder 

 was very hot, and the production of the steam consequently 

 very rapid, the electricity given out was always most powerful. 



