120 



Meatoscope. A speculum for examining a natural passage such 

 as the urethra. 



Mechanical Equivalent of Heat Apparatus. As designed by Dr. 

 G. F. C. Searle, F.R.S. [4, 19.] 



Mechanical Finger. A device for selecting microscopical speci- 

 mens from a mass of material and placing it upon a slide for 

 mounting. [2, 26.] 



Mechanical Locomotive Pyrometer. See Pyrometer, Locomotive. 

 [16.] 



Mechanical Stage. An appliance for attaching to the stage of 

 a microscope for moving a specimen vertically and hori- 

 zontally. [2, 3, 8, 17, 21, 22, 26.] 



Megalethoscope. An optical apparatus in which pictures are 

 viewed through a large lens with stereoptical effects. It is 

 often combined with a stereoscope. 



Megalograph. A form of camera lucida (q.v.). 



Megameter. An instrument for determining longitude by 

 observation of the stars. 



Megaphone. A device for increasing the sound and carrying 

 power of the voice. It consists of a conical funnel with a 

 suitable mouthpiece. It can also be used to increase the 

 power of hearing. [13, 15, 16, 17, 26, 28.] 



Megascope. A modification of the magic lantern, used especially 

 for throwing a magnified image of an opaque object on a 

 screen, solar or artificial light being used. [2, 17, 26.] 



Meker Burner. A special form of Bunsen burner providing for 

 complete combustion of the mixture of gas and air and giving 

 a mass of flame at practically the same temperature through- 

 out. The coolest portion of the flame is hotter than the 

 hottest portion of the ordinary Bunsen flame. 



Mekometer. A two-man rangefinder used in the infantry, 

 consisting of two angle measuring instruments connected 

 by a long wire and operated by two observers. [6, 13, 17, 

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



Melanoscope. An instrument containing a combination of 

 coloured glasses such that they transmit only red light, so 

 that objects of other colours, as green leaves, appear black 

 when seen through it. It is used for viewing coloured 

 flames to detect the presence of potassium, etc., by the red 

 light which they emit. 



Melodiagraph. A contrivance to record the notes of tunes played 

 upon an instrument. 



Melville Stadia. An improved form of levelling staff (q.v.) for 

 facilitating the reading of a staff in hot climates. 



Mercurial Plumb Bob. A special form of plummet made of hollow 

 steel filled with mercury. [13, 15, 17, 21, 24, 27.] 



Mercury Micro-Lamp. An electric light formed by passing a 

 current through mercury vapour and thus producing light 

 of a few definite colours, used for the illumination of 

 microscopic specimens. [2, 3.] 



