450 Sir G. C. Haughton on the Common Nature of 



hair of the human head, and to a spark of diamond; and the 

 accuracy attained may be judged of by the fact, that the same 

 hair having been measured a year afterwards, was found, 

 without any remembrance of the previous measurement, to be 

 what it was before, namely 80°. A specimen from another 

 head which only gave 76° was lost, and the measurement 

 could not be verified, but another hair from the same head 

 being tried it was found to be 82°, a difference which may be 

 accounted for by supposing that all the hairs on the same 

 head are not possessed of equal magnetic intensity at the same 

 moment of time, or by a change in the state of the health of 

 the individual. The measurements may be relied upon as 

 never in excess, though from causes of disturbance, such as 

 the vibration of the house, &c., they must occasionally be 

 capable of being pushed further. No pains however have been 

 spared to obtain the utmost degree of accuracy. Those who 

 shall undertake to repeat these experiments will be best aware 

 of the extreme difficulty of the subject. 



Of the marks of indication. 



Substances not followed by any numerals have been ascer- 

 tained to be magnetic, but have not been measured. 



A implies that no attraction could be discovered. 



The sign + marks that the measurement could be carried 

 further. 



The sign x after 90° is intended to show that the mag- 

 netism is still stronger than that of the highest case of + . 



The double sign of x (that is x x ) is employed to show 

 that the connexion has been effected by the delicate employ- 

 ment of the finger instead of the magnet ; but that the mag- 

 netic intensity of the substance is still not sufficient to attract 

 the needle, whether ferruginous or non-ferruginous of itself. 

 This is the " simpler mode" already aUuded to. 



A marks such substances as attract the needle, though at 

 short distances. 



The magnetic needle was made to connect itself with all 

 the undermentioned substances not followed by 0, which are 

 arranged according to their classes ; and the measurements of 

 such as I had time to ascertain are inserted after each. 



Gold (pure) 90 



Do. (18 carats) 90 



Silver (pure) 90 



Do. (coin) 90+ 



Platinum G5 



Palladium 08 



Cadmium 90 



Tin 90 



\st Class. 



Lead 90 



Zinc 90 



Copper 90-|- 



Mercury 90x 



Antimony CG 



Bismuth 51 



Chromium 90 



Manganese A 



Cohalt A 



Pkiinbago 



Iodine A 



Arsenic 15 



Brass A 



G en nan silver A 



Bell-metal 90 



