88 



Endless Tangent Screw. See Screw. 



Endoscope. An instrument for examining the interior of the 

 rectum. 



Endosmometer. An instrument to measure the rapidity of the 

 passage of a less dense fluid through a membrane or porous 

 septum which separates it from a denser fluid. 



Engine Counter. See Counter. [5, 13, 15, 16, 17, 21, 28.] 



Engine Indicator. See Indicator. 



Engine Power Computer, Pickworth's. A special slide-rule, 

 devised by Mr. Pickworth, for calculating the power, 

 dimensions, and mechanical efficiency of an engine. [15, 21, 

 24.} 



Engine Telegraph. A mechanical instrument used on all steam- 

 ships for transmitting and acknowledging the receipt of 

 orders from the bridge to the engine room. [15.] 



Engineer's Scales. Graduated scales for the use of engineering 

 draughtsmen. [5, 13, 15, 17, 20, 21, 24, 25, 26, 27, 28.] 



Engiscope. A reflecting microscope in which the image is viewed 

 at a side aperture in the tube in a manner similar to the 

 Newtonian telescope. 



Engler's Viscometer. See Viscometer. 



Enormatrope. An optical toy : a card on which confused or 

 imperfect figures are drawn, but which form to the eye 

 regular figures when the card is rapidly rotated. See 

 Thaumatrope. 



Epidiascope or Episcope. A universal microscopic projection 

 apparatus for illustrating lectures and for illuminating and 

 projecting the image of opaque objects upon a screen. [2, 

 3, 20.] 



Equatorial Telescope. See Telescope. [2, 3, 6, 8, 9, 11, 13, 15, 

 17, 18, 20, 21, 25, 26, 27.] 



Erecting Eyepiece. See Eyepiece. [1, 2, 3, 8, 9, 10, 11, 13, 

 15, 16, 17, 18, 20, 21, 22, 23, 24, 27.] 



Erecting Prism.- See Prism. 



Erector. An attachment to a microscope, telescope, or other 

 optical instrument, for making the image erect, instead of 

 inverted. [2, 3, 8, 9, 10, 11, 17, 18, 20, 21, 22, 26, 27.] 



Ergograph. A physiological, experimental apparatus for studying 

 the process of fatigue in the living subject. 



Erinometer. An instrument for measuring the diameter of 

 minute particles of fibres from the size of the coloured rings 

 produced by the diffraction of the light in which the objects 

 are viewed. 



Esthermoscope. An instrument to express the climatic influences 

 which tend to affect the normal temperature of the body. 



Esthesiometer. An instrument to ascertain the tactile sensibility 

 of the human body. 



EtalonF Grating. A? pair of parallel glass plates set with an 

 interval between them to produce by the interference of 

 light a great dispersion. A form of spectrum grating. [10,14. 



