6i 



and counterpoise fixed to a pointer travelling over a circular 

 dial. 



Barometer, Dines 's Self -Recording. A mercury barometer giving 

 records on a chart. [2, 13, 17, 20, 21, 26.] 



Barometer, Fitzroy. A mercury barometer in a wooden frame, 

 usually carved. 



Barometer, Fortin. A mercury barometer. The mercury in the 

 cistern is raised to a fixed point at each observation before 

 the readings are taken. It is safely portable as there is a 

 flexible cistern which allows of the tube being completely 

 filled with mercury. [2, 5, 6, 13, 17, 20, 24, 21, 27.] 



Barometer, Gay-Lussac. A siphon form of mercury barometer. 



Barometer, Glycerine. A barometer in which the liquid used is 

 pure glycerine. 



Barometer, Kew. A mercury barometer. There is no flexible 

 cistern and the scale is contracted to allow for the capacity 

 of the cistern. This pattern cannot be made " portable " 

 in the sense in which the Fortin can. [5, 13, 17, 21, 27.] 



Barometer, King's. A self-recording mercury barometer in 

 which the atmospheric pressure is determined by weighing 

 the column of mercury, instead of by measuring its length. 



Barometer, Marine. A form of mercury barometer for use on 

 board ship, in which the tube is constricted so as to damp 

 the motion of the mercury and prevent sudden oscillations. 

 The frame is suspended in gimbals and attached by an arm 

 to a vertical fixture of the ship. [5, 6, 13, 15, 16, 17, 21, 26, 

 28.] 



Barometer, Mercury. Consists of a column of mercury enclosed 

 in a vertical glass tube deprived of air, the lower end of 

 which dips into a cistern, also containing mercury. The 

 pressure of the atmosphere on the mercury in the cistern 

 supports the column of mercury in the tube, the height 

 varying according to the pressure. [2, 13, 17, 20, 21, 26.] 



Barometer, Water. A barometer in which the variations of 

 atmospheric pressure are measured by the varying height of 

 a column of water. [13, 17.] 



Barometrograph. See Barograph. [27.} 



Baroscope. An instrument designed to show that bodies in air 

 lose as much of their weight as that of the air which they 

 displace. 121.] 



Barry Proudioot Machine Protractor. See Protractor. 



Baseline Apparatus. An apparatus for laying off a standard 

 baseline for trigonometrical survey work. [6, 21, 25, 27.] 



Bathometer. An instrument for measuring the depth of the sea, 

 especially for taking soundings without a measured sounding 

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



Batoreometer. An instrument for measuring minute variations 

 of thickness. The contact of a micrometer screw with the 

 object to be measured is indicated by the passage of an 

 electric current. [4, 19.] 



