774 SEQ. 15. -GEOGRAPHY. 



IV. COMPASSES. 



3151a. COMPASSES, ADMIRALTY PATTERN, IN 

 USE IN HER MAJESTY'S NAVY. 



EXHIBITED BY THE ADMIRALTY HYDROGRAPHIC DEPARTMENT. 



Admiralty Standard Compass. Tripod ; azimuth circle ; 

 light and heavy cards ; spare cap and pivots. Used for steering 

 and taking bearings. 



Plain glass cover when the compass is used for steering. Cover and 

 azimuth circle, for taking bearings, with the card read with a prism, and 

 graduated for measuring horizontal angles. Light card, four compound 

 needles of two laminae each ; ruby cap ; pivots two of hard steel, two pointed 

 with native alloy. Heavy card, four compound needles, two of four laminsB, 

 two of two laminae ; cap of speculum metal ; pivots pointed with ruby. 

 Tripod and sprang, for use of compass on shore. 



This compass can be allowed to rest on india-rubber suspension, by turning 

 the screws marked F and A ; it has the effect of steadying the card when the 

 compass is exposed to vibration. 



Prismatic Azimuth Compass, with tripod, card, spare 

 cap, and pivots. Used for taking bearings on shore, and as 

 a standard compass for small vessels. Card with two compound 

 needles, of two laminae each ; agate cap ; pivots of hard steel. 

 Tripod for use on shore. 



Steering Compass, large size ; with card and spare pivot. 

 For large vessels, card with four compound needles of two 

 laminae each ; cap of speculum metal ; pivot pointed with ruby. 



Steering Compass, small size, with card, spare cap and 

 pivots. For small vessels. Card with two single needles ; cap 

 of agate ; pivots of hard steel. 



Dent's Liquid Steering Compass. For use when the 

 card of the ordinary compass becomes unsteady. 



Liquid, two thirds water, one-third alcohol. Air chamber round upper 

 rim, to allow for the expansion of the fluid from temperature ; aperture for 

 filling when fluid has wasted. Lifter for raising the card off its pivot when 

 required. 



West's Liquid Steering Compass. 



Liquid, of same composition as Dent's. Bowl hermetically sealed, the 

 expansion of the liquid being provided for by having the bottom of the bowl 

 made of flexible corrugated metal. 



Boat's Liquid Compass, in binnacle, with lamp. For use in 

 boats. 



Construction, the same as Dent's Liquid Steering Compass. 



