1883.] On Deviations of the Standard Compass. 



77 



March 15, 1883. 



THE PRESIDENT in the Chair. 



The Presents received were laid on the table, and thanks ordered for 

 them. 



The Right Hon. Joseph Chamberlain was admitted into the 

 Society. 



The following Papers were read : — 



I. " On the Changes which take place in the Deviations of the 

 Standard Compass in the Iron Armour-plated, Iron, and 

 Composite-built Ships of the Royal Navy on a considerable 

 Change of Magnetic Latitude." By Staff-Commander E. 

 W. Creak, R.N., of the Admiralty Compass Department. 

 Communicated by Captain Sir Frederick J. 0. Evans, R.N., 

 K.C.B., F.R.S., Hydrographer of the Admiralty. Received 

 March 1, 1883. 



(Abstract.) 



The period comprised between the years 1855-68 was one of active 

 research into the magnetic character of the armour-plated and other 

 ships of the Royal Navy, and iron ships of the Mercantile Navy. 



Among other contributions to this subject, a paper by F. J. 0, Evans, 

 Esq., Staff Commander R.N., F.R.S., and Archibald Smith, Esq., 

 F.R.S., was read before the Royal Society in March, 1865, relating to 

 the armour-plated ships of the Royal Navy, and containing the first 

 published results of the system of observation and analysis of the 

 deviations of the compass established four years previously. 



From lack of observations in widely different magnetic latitudes, 

 the authors of that paper were unable to define the proportions of the 

 semicircular deviation arising from vertical induction in soft iron, and 

 that arising from the permanent or sub-permanent magnetism in hard 

 iron. 



Daring the last fifteen years vessels of all classes — except turret 

 ships — have visited places of high southern magnetic inclination or 

 dip, and the analysis of the deviation of their standard compasses has 

 been made, showing the constants for hard and soft iron producing 

 semicircular deviation. 



