1826.] Royal Society. 69 



voyages, though he observed the effect, does not seera to have 

 thought it worthy of correction, and that even when making a 

 set of miniite observations on variation ; he says, in his paper in 

 the Transactions, * We know by experience how little the iron 

 guns on board ship affect the needle.' This, however, probably 

 arose from the circumstance, that he was never in very high 

 latitudes." Walker, in his Lecture on Magnetism, first called 

 the attention of navigators to the subject; Capt. Flinders 

 broupht it before the notice of the Admiralty ; and the late 

 arctic expeditions have afforded the fairest and fullest opportu- 

 nities of determining the fact. 



" Mr. Barlow, after making a number of experiments on the 

 pheenomena presented by different large masses of iron, and 

 recurring to the principle that the contiguity of a small mass 

 makes it equal or superior in power to larger masses ; and that 

 the attractions and repulsions diminish as the square of the 

 distance, thought of two methods of correcting the errors ari&ing 

 from the magnetism of the iron in ships ; one by compensating, 

 the other by doubling them, by means of small masses, or thin 

 plates of iron placed near the compass, the relation of which to 

 the magnetism of the earth, the iron in the ship, and ihe needle, 

 should be determined by experiments." 



Mr. Barlow has adopted the last method in practice, and its 

 utility has already been proved by Captains Baldey, Sabine, and 

 Parry, and other able and enlightened officers. 



" The Royal Society " the President continued, "has always 

 since its first institution, given particular encouragement, and 

 paid particular attention to those departments of science which 

 are strictly practical, and offer the best vindication and the 

 highest praise of the experimental and inductive method, 

 bnnging philosophy, as it were, from the heavens to the earth, 

 and fixing her abode, not in visionary, splendid, and airy 

 edifices, but amongst the resting places and habitations of men. 

 To point out an useful application of any doctrine or discovery 

 has always been their highest pride, and fortunately they have 

 had many noble opportunities and examples. Indeed there is 

 scarcely any instance of a considerable advance made in the 

 knowledge of nature without being soon connected with some 

 tangible benefit or advantage ; as light is almost always accom- 

 panied by heat, the illuminating by the productive and nourish- 

 ing principle. 



** In conformity to the usages and feelings of the Society, the 

 Council has awarded the medal to Mr. Barlow, who, by reason- 

 ing and experimenting upon a few simple facts long known, but 

 never applied, has founded an useful invention, tending to the 

 perfection of an instrument, the most important, perhaps, to 

 Britons, of all those which have been the results of scientitic 



