284? Mr. R. Phillips on the Magnetism of Steam. 



pended needle, with its directive force partly neutralized by 

 placing near it another fixed magnet. In some experiments 

 this was done by attaching a magnetized needle to a piece of 

 copper wire sliding through a cork stuck on the inside of the 

 beaker; this fixed needle lay horizonally under the suspended 

 needle, and the degree to which it was necessary to balance 

 the earth's magnetism was effected by means of the copper 

 wire. As this adjustment, although in other respects excellent, 

 could not be executed with sufficient rapidity, the needle was 

 subsequently removed from the copper wire, and the swinging 

 needle was partly balanced by a steel magnet placed at a di- 

 stance. When the fixed magnet was applied, it brought the 

 marked end of the suspended needle to point about 20 or 30 

 degrees west of the position which it otherwise took up; the 

 needle of the galvanoscope stood rectangularly to the axis of 

 the coils and on the east side. The swinging needle was 1*8 

 inch long, and its point, which was observed in the micro- 

 scope as before (3, 4.), pointed to the south. A and C stand 

 for the same sides of the field of view, and the general mode 

 of using the instrument and the zinc screen was as formerly. 

 It may be as well to mention that the microscope inverted. 

 The steam was usually employed at pressures ranging from 

 15 to 25 lbs. on the inch, the magnetism, so far as my expe- 

 riments with coils have yet gone, being sensibly the same 

 between these limits. A principal reason for using these 

 lower pressures was, that the temporary joints and pewter 

 coils of the discharging apparatus were much more easily 

 kept in order than at the higher pressures. The stop-cocks, 

 T-pieces, &c, were such as are generally used about oxy- 

 hydrogen blowpipes, and care was taken that they should have 

 sufficient steam-way. The temporary joints were made as 

 follows: having adequately supported and brought together 

 the two ends which it was desired to unite, a strip of common 

 sheet caoutchouc about ~ inch wide was wound once round 

 the tubes at the juncture, and then a strip of oiled silk about 

 an inch wide was wound twice round outside the caoutchouc 

 and slightly bound on with fine thread. Three or four rounds 

 of a piece of tinfoil rather wider than the silk were now laid 

 on and carefully rubbed down smooth, and then well bound 

 on with strong thread. 



131. A pewter tube 5 feet 7 inches long, having ■£•§ inch for its 

 internal, and /^ inch for its external diameter, was inserted in 

 another pewter tube rather shorter, having an internal diameter 

 about /q mcn an d an external diameter of ^ inch ; the whole 

 was then made into a dense cylindrical coil, 3*3 inches long, 

 having a cylindrical space 1*2 inch diameter to receive an iron 



