iv 



In 1859 he read a paper at the Royal United Service Institution, 

 on the magnetism of iron ships, showing all that had been done np to 

 that date in acquiring a knowledge of their magnetism and the treat- 

 ment of their compasses. 



His next paper was a report to the Admiralty of the magnetic cha- 

 racter of the various types of iron ships in the Navy, and of the 

 " Great Eastern " steamship. The results of this paper were to show 

 the best magnetic direction for building an iron ship, the best position 

 for placing her standard and other compasses, and the various sources 

 of error affecting a compass under the most favourable conditions. 

 This report was communicated to the Royal Society, and printed in 

 the Transactions for 1860. 



A joint paper on the proper length and arrangement of the needles 

 on a compass card, with exact information as to proper arrangement 

 of magnet and soft iron correctors with respect to it, was communi- 

 cated to the Royal Society in 1861. 



In 1862, the Admiralty published " The Manual for the Deviation 

 of the Compass in Iron Ships ;" this important work was the result 

 of the joint labours of Evans and Archibald Smith. It was imme- 

 diately translated into the principal European languages, and became 

 the text-book of the maritime world. On the introduction of new 

 types of armour-plated ships, new editions of the work became from 

 time to time necessary, and were published. 



In 1865 the joint authors produced another important paper on the 

 magnetic character of the armour-plated ships of the Navy up to that 

 date, The novelty of the form of ships thus discussed rendered the 

 results of more than usual interest, and proved among other things 

 with what degree of confidence compasses might be placed in positions 

 where armoured protection would be afforded; this paper was also 

 printed in the Transactions of the Royal Society. 



The practicability of determining the magnetic coefficients without 

 the labour of swinging, and the heeling error, without inclining the 

 ship, was also demonstrated, and has been practically adopted in the 

 Navy, with great saving of labour and expense. 



In 1865, on the retirement of Captain Becher from the Hydrographic 

 Department, Captain Evans succeeded him as Chief Assistant to the 

 Hydrographer, retaining the position of Chief of the Magnetic 

 Department. From this time his practical duties in regard to compass 

 management devolved on his successor, though he never relaxed his 

 investigations, or wearied in his devotion to the science of terrestrial 

 magnetism, and in 1870, desiring to present the subject of compass 

 deviation in a less elaborate form than had been done in the former 

 publication, he brought out his " Elementary Manual," a work which 

 was very well received, and was also translated by the maritime 

 nations. 



