Robinson's Centrifugal Force Apparatus. See Centrifugal Force 



Apparatus. [19.] 



Robinson Magnets. See Magnets. [19.] 

 Rod Level. -A level (q.v.) with fitting for use on a vertical or 



horizontal rod. [21, 27.] 

 Roller Beam Compass. See Beam Compass. [2, 6, 13, 15, 20, 



21, 24, 26, 27.] 

 Rolling Instrument, Mallock's. A form of parallel rule (q.v.), 



adapted for drawing parallels on charts on board ship. It 



has the property of rolling in two directions at right angles 



to each other. [13, 21.] 

 Rolling Parallel Rule. See Parallel Rule. [2, 5, 6, 13, 15, 16, 



17, 20, 21, 24, 25, 26, 27, 28.] 



Roof Prism. See Prism. [1, 2, 3, 8, 9, 12, 13, 14, 18, 20, 23, 26.] 

 Rosenhain Calorimeter. See Calorimeter. [4.] 

 Rotameter. A small wheel instrument for measuring distances 



on maps or the like. [5, 13, 15, 17, 20, 21, 24, 26, 27, 28.] 

 Rotascope. An instrument on the same principle as |the 



gyroscope (q.v.). 



Rousseau's Densimeter. See Densimeter. 

 Ruhmkorff's Coil. An induction coil (q.v.). [26.] 

 Rumford's Photometer. See Photometer. 

 Rutherford's Maximum and Minimum Thermometer. See 



Thermometer. 

 Rutherford Pnsm.See Prism. [3, 13, 26.] 



Saccharimeter or Saccharimeter Polariscope. A foim of polari- 

 scope (q.v.) for testing sugar solutions by polarised light. 

 [2, 3, 13, 14, 15, 17, 19, 20, 21, 22, 26.] 



Saccharometer. See Hydrometer. [5, 6, 13, 15, 17, 20, 21, 25, 26.] 



Salinometer. An apparatus for ascertaining the salinity of 

 water or the density of brine in the boilers of marine 

 steam-engines. [5, 6, 13, 15, 16, 17, 21, 26, 28.] 



Salometer. See Salimeter. [5.] 



Salimeter. An instrument for measuring the amount of salt 

 present in any solution. [13, 15, 17.] 



Salinity Recorder. A development of the recording densimeter 

 (q.v.) for obtaining a record of the changes in the salinity of 

 river or other water. [4.] 



Sampling Bottles (Mine Explosions Apparatus) (q.v.). For ex- 

 tracting samples of gas from the gallery during the explosion. 



w 



Sankey's Metal Bending Tester. See Metal Bending Tester. 

 Sapphire Cap. A metal cap with sapphire setting used in 



magnetic compasses. [13, 15, 16, 17, 21, 24, 25, 27, 28.] 

 Sceptre Recorder. An instrument for recording the depth of 



water under a ship. [28.] 



Sceptre Sounding Machine. See Sounding Machine. [13, 28.] 

 Schumann Plates. Sensitised photographic plates sensitive to 



light of extremely short wave-lengths. 



