76 



W. Sturgeon, Esq., on the 



more tedious modes of inquiry being thus rendered unneces- 

 sary. 



16. I have found that a convenient and efficacious mode of 

 examining bodies the magnetic actions of which are very 

 very feeble, and others in which magnetism has but a ques- 

 tionable existence, is by means of an apparatus represented 

 by the accompanying figures. 



Fig. 1. 



Fig. 2. 



^^ 



Fig. 1 is that part of the apparatus in which the speci- 

 mens to be examined are placed. It consists of a light cy- 

 lindrical wooden rod A B, about 12 inches long, and sus- 

 pended by a few parallel fibres of silk F F, from the cocoon. 

 The end B is furnished with a light slip of card-paper and 

 two loops of horse-hair, for the purpose of holding the speci- 

 men ; say a half-crown, for instance, as represented in the 

 figure, which is counterbalanced at the other end of the lever 

 by a sliding weight w. This part of the apparatus is en- 

 closed in a rectangular box. Fig. 2, whose ends, top, and one 

 of its sides, are of glass, and a brass tube rises from the 

 middle of the top, in which hangs the silken fibres. The 

 head of this tube sustains the fibres and their appendages, 

 and can be turned in any horizontal direction for the adjust- 

 ment of the lever to a parallelism with the sides of the box. 



The glass parts of the box are sustained by a light maho- 

 gany frame, with a bottom of the same kind of wood. The 

 ends and sides are fixed, but the top, which consists of two 

 sliding parts, can be removed at pleasure, for the purpose of 

 introducing the hands for the adjustment of the apparatus 

 within, and replaced when the specimen has been accurately 

 counterpoised, a process which is still farther facilitated by 

 the introduction of the hand at one side of the box, which is 



