" racter as to render them available to less highly trained intellects, he 

 " derived at my request, from Poisson's fundamental equations, simple 

 " and practical formula), including the effects both of induced magnetism 

 " and of the more persistent magnetism produced in iron which has 

 " been hardened in any of the processes through which it has passed. 

 " The formula) supplied the means of a sufficiently exact calculation 

 " when the results were finally brought together and coordinated. They 

 " were subsequently printed in the form of memoranda in the account 

 " of the survey in the * Philosophical Transactions ' for 1843, 1844, and 

 " 1840. 



" The assistance which, from motives of private friendship and scien- 

 " tific interest, Mr. Smith had rendered to myself, was from like motives 

 " continued to the two able officers who had successively occupied the 

 " post of Superintendent of the Compass Department of the Navy; and 

 " the formula) for correcting the deviation, which he had furnished to 

 " me, reduced to simple tabular forms, were published by the Admiralty 

 " in successive editions for the use of the Royal Navy. 



" As, in the course of time, the use of steam machinery, the weight of 

 " the armament of ships of war, and generally the use of iron in vessels, 

 " increased more and more ; the great and increasing inconvenience 

 " arising from compass irregularities were more and more strongly felt, 

 " and pressed themselves on the attention of the Admiralty and of 

 " naval officers. 



" An entire revision of the Admiralty instructions became necessary ; 

 " Mr. Smith's assistance was again freely given ; and the result was the 

 " publication of the 'Admiralty Manual ' for ascertaining and applying 

 " the deviations of the compass caused by the iron in a ship. 



"The mathematical part of this work, which is due to Mr. Smith, 

 " seems to exhaust the subject, and to reduce the processes by simple 

 " formula) and tabular and graphic methods, to the greatest simplicity of 

 "which they are susceptible. Mr. Smith also joined with his fellow- 

 " labourer, Captain Evans, E.K.S., the present Superintendent of the 

 " Compass Department of the Navy, in laying before the Society several 

 " valuable papers containing the results of the mathematical fcheorv 

 " applied to observations made on board the iron-built and iron-plated 

 " ships of the Royal Navy." 



This is not an occasion for explaining in detail the elaborate investiga- 

 tions sketched in the preceding statement by Sir Edward Sabine ; but 

 the writer of the present notice, having enjoyed the friendship of Archi- 

 bald Smith since the year 1841, and having had many opportunities, 

 both in personal intercourse and by letters, of following the progress 

 through thirty years of his work on ships' magnetism, may be permitted 

 a brief reference to some of the points which have struck him as most 

 remarkable : 



