92 Physical Discovery. 
This discovery, is not a mere speculation,—a simple project, but 
it is an invention that has been tested by experiments, which the au- 
thor has actually made. We have had the satisfaction of seeing them 
made in our presence; and we, moreover, have in our cabinet, the 
first compass of this kind, which the author has constructed and con- 
fided to us. The explanation which he has given us, of his magnetic 
process, is equally curious, and satifactory. 
The little needle, according to his theory, endeavors as much as it 
is enabled, and on its own account, to approach the north like all other 
magnetic needles, to within about twenty degrees. Itis counteracted ~ 
in this direction, by the large needle, which, of right, preoccupies that 
position, and takes possession of it; but as the effort of the small nee- 
dle cannot be inconsequential, its rival, finds itself to be pushed a lit- 
ile farther, this impulsion acting by reason of the quantity of inherent 
power in the little needle. 
The author cencludes that the deviation which is observable in the 
common compass, results from an actual defect in the magnet, that 
is, from a weakness in its directing power; and that it is from this de- 
fect in its power, that the common magnetic needle does not now 
point to the trué north, as it did in 1666, whereas by associating with 
it, another needle, it is rendered, by this auxiliary combination, that 
nineteen twentieths degree of power which it wants at the present 
time to attain this object. 
Such a discovery as this cannot but excite the curiosity of all the 
friends of the arts; and we consider it as calculated to extend the 
sphere of acquired knowledge, on the character and properties of the 
magnet, a complete union of which, according to some philosophers, 
should result in a theory of longitude. At all events, we can, with 
reason, flatter ourselves, (thanks to the invention which we have made 
public,) that the mariner’s compass, is advancing towards perfection. 
In fact, the common magnetic needle has only one cause of direction, 
which is deranged by the least extraneous impulse, whereas the new 
needle, combined, as has been described, tends to a point, where it 
is fixed by two directive causes, which form an angle, and by which 
itis, in a manner, confined, which necessarily, renders it less unsta- 
ble, less capricious, and Jess subject to variation. 
