734 SEC. 15. GEOGRAPHY. 



2989. Scales, ivory ; set of 6. 



2990. Beam Compass, wood. For the accurate measure- 

 ment of long sides in projecting triangulation. 



2991. Drawing Instruments ; magazine set. 



2992. Drawing Instruments, for service in boats. 



INSTRUMENTS OCCASIONALLY FURNISHED TO OFFICERS ENGAGED 

 IN NAVAL SURVEYING EXPEDITIONS. 



2993. Reflecting Circle. Troughton. 



2994. Sextant, Travelling, small. 



2995. Sextant, Observing, with micrometer and indicators. 

 Davis. 



2996. Sextant, Sounding, Double. Beechey. 



2997. Sextant, Pocket, Double. George. 



2998. Dip Sector. By Troughton. For measuring the angle 

 between the apparent and true horizons, from an elevation above 

 the surface of the earth. 



2999. Artificial Horizon, portable. George. 



3000. Stadiometer. Blakey. An ordinary telescope fitted 

 with a sliding measure and linear arrangement on object-glass ; 

 designed for the purpose of determining the distance apart of two 

 ships, the height of the masthead of the second ship being known. 



3001. Optical Opposite. Raper. An instrument for deter- 

 mining and preserving a position in a direct line between two 

 objects. 



3002. Beam Compasses, tubular. 



3003. Beam Compasses, bar, metal, 



SOUNDING MACHINES AND APPARATUS USED BY H.M. SHIPS IN 

 DEEP SEA EXPLORATION. 



3004. Clam, for bringing specimens of the sea bottom. Sir 

 John Ross; date 1818. Designed and used by Sir John Ross in 

 H.M.S. "Isabella" in Baffin Bay. 



The claw is kept open by hinged arms within ; whilst thus open, the outer 

 case is kept up, and a spike connected with the arms projects below the 

 claw. On striking bottom the spike forces the arms up ; this releases the 

 outer case ; as the claw closes, the case slides down, and the contents in claw 

 are secured. 



