$06 Mr. R. Phillips oji the Magnetism of Steam. 



is in the same horizontal plane as the central line of the path 

 of the steam, than when the galvanoscope is placed so that 

 the steam may pass equally near to both needles. I have 

 occasionally observed the swing to be five or six times greater 

 in one position than in the other ; but sometimes the swing is 

 the same in either position. I have not perceived a similar 

 effect with any other jet. 



14-. A pewter tube 6 feet long, having a bore 2% inch dia- 

 meter, was coiled up after the fashion of the wire of a galva- 

 nometer: it made six convolutions. One end of the tube 

 was jambed on the brass jet (9.), and the coil stood horizon- 

 tally like the coil of a galvanometer; the zinc shield was 

 brought nearly close to the coil, and the height of the galva- 

 noscope was adjusted so that the coil might act on both the 

 upper and lower sides of the lower needle ; the steam entered 

 on the upper side of the coil in the same direction as before. 

 By this arrangement I succeeded in producing a mai'ked 

 swing with steam of a very low pressure, I think below 5 lbs. 

 on the inch ; but I did not exactly ascertain the amount of 

 this low pressure, because the safety-valve of the boiler is not 

 graduated below 4C lbs. As the pressure rose, the power 

 exerted on the needles became greater ; and at 40 lbs. on the 

 inch, a few puffs of steam caused the needle to move through 

 the whole length of the micrometer; the motion, when the 

 steam was turned on, being towards C. 



15. Instead of allowing the steam to pass continuously 

 through the tube during the whole of each alternate vibration, 

 it was shut off before the vibration was completed. The swing 

 was now much less, showing that it was not the first gust of 

 steam which alone moved the needles; and this agreed with 

 the visible motion of the needle, which manifestly increased 

 in velocity after it began to move. 



16. Water being placed in the condenser of the hydro- 

 electric machine did not sensibly alter the force exerted on 

 the needles by the coil. 



1 7. The coil was now attached to the boiler by means of a 

 piece of brass, the steam-way of which was so large that the coil 

 only might be looked upon as opposing the exit of the steam. 

 Various pressures were tried, as the boiler became heated, up 

 to 40 lbs. per inch. A lead pipe was, in this experiment and 

 frequently afterwards, placed at a short distance from the coil 

 to catch the steam and convey it up a chimney, whereas in 

 former experiments it had freely escaped into the apartment ; 

 everything else remained as before (14.). The needles began 

 to be affected at a very low pressure; and as the pressure in- 

 creased, the swing became certain and steady, the needle 



