A nalysis of Mr Barlow’s Essay on Magnetic Attractions , 205 
attraction of vessels, the object for which the course of experi- 
ments was specifically undertaken. 
Aware, however, of the consequences of introducing difficult 
computations into the daily reckonings of a ship’s course, the 
author endeavoured to discover some method of performing the 
same experimentally; and, after one failure, he succeeded in 
every respect to his wishes ; although it appears, by the letter to 
which we have already alluded, that he has since still further 
improved the method described in his Essay ; and that he has, 
by an order of the Admiralty, put this method in practice on 
board his Majesty’s ships the Leven and Conway: and we un- 
derstand that Captain Parry takes out one of his correcting 
plates in the Fury , in the present voyage, where the efficacy of 
the experiment will be submitted to a severe, but to a candid 
trial. 
We have no hesitation in stating, that, as far as our know- 
ledge of magnetism extends, all the laws which we have been 
describing are new facts in that science. By means of them 
we may compute, and by the most simple rules, the effect which 
a mass of iron will produce on the compass in every situation, 
and in any part of the world ; and we ask, Could this have 
been done prior to Mr Barlow’s discoveries? — and if so, In 
what works are those laws given ? 
We insist upon these questions, because it appears that some 
attempts have been made to show that there is nothing striking- 
ly new in these results. In the letter already alluded to, Mr 
Barlow says, — 
64 It is pretty generally known, that soon after I had arrived 
at the leading principles of the above laws, I communicated the 
results to the Royal Society, and that the Committee refused 
publishing my memoir, assigning (as I have found since my 
book has been published) as a reason, that similar experiments 
had been made in Denmark many years ago, 
44 This is stated in a letter from the late Sir J, Banks to the 
late General Mudge, of which the following is a copy/’— 44 Soho 
Square , May 13. 1819.— ~My dear Sir, I have received Mr 
Barlow’s paper, and have placed it in the hands of the Se- 
cretary of the Royal Society, to be read at the first meeting. 
It gives me much satisfaction to see that experiments have been 
