92 



Finder, Wright's. A finder consisting of a square of 25 mm. 



divided into 25 mm. engraved on the stage of a microscope. 



[2, 10, 22, 26.} 



Fire-Damp Photometer. See Photometer. 

 Flame Manometer. See Manometer. 

 Flank Observation Computer, Notcutt. An instrument designed 



to determine the necessary corrections when ranging from 



a flank. [75.] 

 Flash Point Apparatus. An apparatus for testing the flashing 



point (i.e., the temperature of ignition) of oils by bringing 



a flame into momentary contact with the vapour. There 



are many forms. [13, 15, 17, 21.] 

 Flash Point Apparatus, Abel's. For petroleum mixtures. [13, 



15, 17, 21.] 

 Flash Point Apparatus, Abel-Pensky. The same apparatus as 



Abel's, with addition of clockwork to open the cover and 



depress the test flame. [13, 15, 17.] 

 Flash Point Apparatus, Gray's. For heavy mineral oils. [13, 



15, 17.] 

 Flash Point Apparatus, Pensky-Marten's. For the testing of 



heavy oils. [13, 15, 17.] 



Flash Test. See Flash Point Apparatus. [13, 15, 17, 21.] 

 Fletcher's Anemometer. See Anemometer. [13, 15, 17, 21.] 

 Fletcher's Inclined Plane and Trolley Apparatus. An apparatus 



for demonstrating the laws of acceleration and impact. [19.] 

 Fletcher's Thenno-Hydrometer. See Thenno-Hydrometer. [13, 



15, 21.] 



Flicker Photometer. See Photometer. 

 Flinder's Bar. A soft iron bar which is fixed generally on the 



forward side of the ship's compass to compensate the error 



caused by the induced magnetism in the vertical iron on the 



ship. [13, 15, 16, 17, 28] 



Floating Collimator or Intersector. See Collimator. 

 Floating Photographic Telescope. See Telescope. [13, 15] 

 Flour Hopper Thermometer. See Thermometer. [5, 6, 13, 15' 



17, 21.] 

 Flow Recorder. An instrument for recording the volume of gas 



or air passing through a pipe. [4.] 

 Flow Recorder, Cambridge. 



Flue Gas Thermometer. See Thermometer. [5,13,15, 16, 17, 21.] 

 Fluid Compass. See Compass. 

 Fluid Level Indicator. For indicating the fluid or liquid level in 



oil and spirit tanks of aeroplanes, etc. [2, 13 15.] 

 Fluidimeter, Phillip's. 

 Fluid-Lens. See Lens. 

 Fluid-Meter. See Meter. [4] 



Fluxmeter. An instrument for the exploration and, in con- 

 junction with a galvanometer, estimation of the strength of 



magnetic fields. [4, 19.] 



