4'42 Sir G. C. Haughton 07i the Conunon Nature of 



me that the magnetism might be much increased by keeping 

 it in close contact for a short time with a more powerful mag- 

 net. The result fully justified this anticipation, and the at- 

 tractive affinity between the needle and the substance was 

 immediately augmented ; but generally in those cases where 

 no attraction had been already discovered, none made its ap- 

 pearance by the additional magnetic influence to which it 

 was subjected. Want of health and time prevented me from 

 establishing more than the general character of these last facts, 

 but I shall have to speak more fully of the particular cases 

 tried as I proceed. 



Among the few substances placed in contact with the bar- 

 magnet for the purpose of increasing their magnetic energy, 

 the following seem to be totally uninfluenced by its presence, 

 viz. copper, lead, marble, selenite, alum and pure lac. 



The following experiment will show how strong the con- 

 nexion often is that takes place between the needle and non- 

 ferruginous substances. A magnet having been brought ver- 

 tically over the needle contained in a small box-compass, which 

 was screened by a piece of crown-glass, the needle attached 

 itself instantly, or, to speak moxe exaciXy, per salttim, so firmly 

 to the glass, that the box might be pushed backwards and 

 forwards from one end of the chimney-piece on which it lay 

 to the other, without contact being broken ; and in this state 

 it continued for six days, though the door of the room was 

 often shut with considerable force; and the connexion was at 

 last only broken by the box having inadvertently received a 

 shock from the hand. The contact was occasionally renewed 

 by the same means, sometimes for two or three days, and 

 always continued till broken at pleasure. This experiment 

 will not succeed if the pivot of suspension is either too high 

 or too low ; and the needle must be of the pointed kind. 



It is proper to describe here a very useful electrometer 

 which 1 employed to ascertain whether substances exhibit any 

 electrical effects. It is of extreme simplicity, and is not merely 

 much more sensitive than that employed by Haiiy, but even 

 more so than the most delicate gold-leaf electrometer. It 

 consists of a magnetic needle five-eighths of an inch in length, 

 with an agate cap. Upon each end of the needle a piece of 

 oaten straw, one inch in length and about one-thirtieth of an 

 inch in diameter, is fixed. When this part of the system 

 is placed, as in the former case, on the point of a sewing- 

 needle with a brass stand, the instrument is complete. It has 

 an additional advantage over that of Haiiy, that, owing to the 



