510 Mr. R. Phillips on the Magnetism of Steam. 



and west. The shield stood ^ inch at its nearest part from 

 the end of the coil, and the galvanoscope was adjusted so that 

 the lower needle was opposite to the coil ; the steam circulated 

 in the same direction as before (14, 26.). At 40 lbs. four puffs 

 of steam produced a swing about one-fourth across the micro- 

 meter, and the swing was not very much stronger at any lower 

 pressure. The copper pan, which had previously been placed 

 in position under the coil, was now filled with water, by which 

 the coil was about half-covered. The first motions of the 

 needle were not very powerful ; but alter three or four puffs, 

 which heated the water about the coil, one puff of steam would 

 move the needle from A quite out at C; the swing was in the 

 same direction when there was no water in the pan. 



30. The cylindrical pewter coil had a turn or two opened 

 out, in order to give sufficient length between the brass con- 

 necting piece and the coil to allow the latter to be immersed 

 in the water of the copper pan. The gun-barrel was placed 

 in the coil, and was supported by wires attached to the copper 

 pan, and so prevented from touching the coil ; the gun-barrel 

 projected about ^ inch beyond the end of the coil on the side 

 nearest to the galvanoscope. The optical tube of the galva- 

 noscope was removed, and the hole in the cover was closed 

 with a piece of glass. The steam was used at about 40 lbs. 

 on the inch. After the water in the copper pan had been 

 heated, I could easily by successive puffs of steam produce a 

 vibration through an arc of 20 or 30 degrees. 



31. Putting together these gun-barrel experiments, and 

 that with condensed air (24.), I come to the conclusion that a 

 difference of temperature is necessary to produce these peculiar 

 magnetic effects ; which accounts for the greater force of the 

 first blast of steam (22.), and for the superior force of a jet 

 (11.). Also the similarity which exists between the magnetic 

 effects of the steam current, and the magnetic effects of the 

 voltaic current, both as regards magnets and soft iron, renders 

 it nearly or quite certain that this force of the steam is mag- 

 netism. 



32. Now a jet of steam, even when mixed with much water, 

 is an excellent non-conductorof electricity; for when discharged 

 from an Armstrong's jet, it is seen that electricity even of a 

 very high intensity cannot pass through it, and a jet of dry 

 steam must be at least as good a non-conductor ; hence the jet 

 of steam (11.) cannot be travelled by any feeble current of 

 electricity, a thermo-electric current for instance. Again, this 

 magnetic effect of the steam must be independent of any elec- 

 tricity carried forward by the steam, as when discharged by an 

 Armstrong's jet ; for the greatest amount of electricity which 



