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V. A new Suspension of the Magnetic Needle, intended for the 
Discovery of minute Quantities of Magnetic Attraction : also 
an Air Vane of great Sensibility ; with new Experiments on 
the Magnetism of Iron Filings and Brass. By the Rev. 
A, Bennet, F.R.S. Communicated by the Rev. Sir Richard 
Kaye, Bart. F. R. S. 
Read January 2 6, 1792. 
To manifest the various degrees of attraction between mag- 
nets and ferruginous bodies, different methods have been used. 
The substance to be tried has either been simply brought into 
contact with the magnet, or lias been made to float on water 
or mercury. Needles are commonly made to rest horizontally 
on sharp-pointed wires, and as an improvement on these me- 
thods, Mr. Cavallo has suspended a needle by a chain of 
horse-hair, consisting of five or six links, which move very 
freely in each other, and allow the needle to turn more than 
a whole revolution round its centre. By comparing this 
needle with others of the best sort in use, he found it much 
more sensible. Others have suspended the needle by fine 
threads, or silk : but as these, on turning round a few times, 
will cause the needle to deviate from its meridian by twisting, 
they are certainly objectionable. 
After considering each of the above methods, and trying 
some of them in November, 1789, 1 suspended a small sewing 
MDCCXCII. M 
