156 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



memoir of Sir Edward Sabine show that the second pole of 

 magnetic force of the northern hemisphere is situated in the 

 eastern portion of the Asiatic continent, probably not far from 

 the centre of China. Trans. Hoy al Society, 1873, 353. 



THE NEW MARINE COMPASSES OF MESSES. EITCHIE & SONS. 



According to the recent annual report of the Secretary 

 of the Navy, the liquid compass manufactured by Messrs. 

 Ritchie & Sons, of Boston, is not only sound in principle, but 

 convenient and reliable in use, satisfying the three funda- 

 mental desiderata of sufficient magnetic power, great stabil- 

 ity or steadiness, and extreme sensibility. In the first par- 

 ticular, only, does Professor Greene report that it possibly 

 admits of being improved. In the compasses now manufact- 

 ured under his supervision, a new card-circle has been de- 

 vised, insuring greater precision in all the details of the 

 formation of the compass-card itself. Two card magnets are 

 permanently attached to the compass -card. The weight 

 pressing upon the pivot is only about fifty grains at the mean 

 temperature ; but even with this there is an appreciable wear 

 of the agate bearings, and it is proposed to test the use of 

 sapphire instead of agate. The azimuth circles are so made 

 that they are interchangeable upon every bowl of the same 

 class, but, in spite of the attention given to all the details of 

 the compass, there must be accurate, reliable tests of the act- 

 ual condition of the instrument when completed ; otherwise 

 no certainty can be had as to the excellence of its perform- 

 ance. Report of the Secretary of the Navy, 1873, p. 80. 



COMPASS DEVIATIONS. 



Among the additions to the Bureau of Navigation of the 

 Navy Department at Washington has been the construction 

 of a compass observatory, under the direction of B. F. Greene, 

 who was recently appointed professor of mathematics and 

 made superintendent of compasses. The important matter 

 of the deviation of the compasses on board of both iron and 

 Avooden vessels has undoubtedly been too much neglected in 

 this country, although its importance has long been fully rec- 

 ognized, first of all in England and France, and later also in 

 Australia, Russia, and Germany. In a previous volume of the 

 Annual Record will be found a notice of the memoir of Pro- 



