n6 



Logograph. An instrument for giving a graphic representation 

 of the motion of the air-waves of speech. It consists of a 

 horn connected with a diaphragm, which, by means of a 

 pen, records its vibrations on a traversing strip of paper. 



Logometer. A scale for measuring chemical equivalents. 



Log Ship. A thin flat piece of board in the form of a quadrant 

 of a circle attached to the log-line. [13, 15, 16, 21, 28.] 



Lorgnette. Eyeglasses of elaborate design, with handle to hold 

 in the hand. [2, 9, 15, 17, 20, 21.] 



Louchettes. Opaque spectacles, with perforations in the centre 

 to force the eyes to assume their normal positions. 



Lovibond's Tintometer. See Tintometer. [3, 5, 13, 17, 21, 26.] 



Lowry's New Pattern Thermostat. See Thermostat. 



Lucernal Microscope. See Microscope. [26.] 



Lucimeter. An instrument for measuring the intensity of light ; 

 a photometer (q.v.). [13.] 



Lumeter (Holophane). A portable photometer (q.v.). [3.] 



Luminous Geh Plate. A glass plate for producing extended 

 spectra by the interference of light reflected from its 

 surfaces. [14.] 



Lummer-Gehrcke Parallel Plate. A very accurate plane-parallel 

 plate of glass which acts as a diffraction grating (q.v.). [2, 

 3, 10, 14, 20, 26.] 



Lunette. A species of convexo-concave lens for spectacles. 

 [17, 26.] 



Lunge's Nitrometer. See Nitrometer. 



Lux's Gas-Balance. A delicate instrument for determining the 

 weights of gases. 



Lysimeter. An instrument for measuring the water that per- 

 colates through a certain depth of soil. 



Macfarlane and Caldwell's Gas Analysis Apparatus. See Gas 

 Analysis Apparatus. [17.] 



Mackey's Cloth Oil-Tester. See Cloth Oil-Tester. [5, 13.] 



Macrometer. An instrument for determining the size of distant 

 or inaccessible objects by means of two reflectors on a 

 common sextant. 



Maddox Rod. An instrument used in sight-testing. 



Magic Lantern. See Lantern. [2, 20.] 



Magnet. A body charged with or possessing the property of 

 magnetism, such as the loadstone. Artificial magnets are 

 usually made of bars of steel, magnetised by rubbing them 

 with another magnet, or by coiling a wire in the form of a 

 helix round a core of soft iron or steel and sending an 

 electric current through the wire. In the latter case the 

 magnet is termed an electro-magnet. [13, 15, 16, 17, 19. 

 26, 28.] 



Magnets, Robinson. Spherical-ended magnets with true poles. 



