139 



Picknometer. See Pycnometer. [21.] 



Piokworth's Engine-Power Computer. See Engine-Power Com- 

 puter. [15, 31, 24.] 



Piecework Balance Calculator, Smith-Davis. A wheel form of 

 calculator for money or time calculations in connection 

 with piecework. [15.] 



Piezometer. An instrument for measuring pressure or the sense 

 of it. 



Piezometer. An instrument for measuring the compressibility of 

 liquids. A gauge connected with a water main to show 

 the pressure at that point. [20.] 



Pillar Compasses. See Compasses. [2, 5, 6, 13, 15, 16, 17, 21, 

 24, 27.] 



Pioscope. A milk-testing instrument. 



Pipette. A glass measure or tube having a pointed end and 

 small aperture, graduated so as to deliver a fixed quantity 

 of liquid when filled to a definite mark at a definite temper- 

 ature. [2, 13, 17, 20, 26.] 



Pitchometer. An instrument for determining the pitch of a 

 propeller. [13, 15, 17, 21.] 



Pit Hygrometer. A portable form of Mason's hygrometer (q.v.) 

 for use in coal mines. [5, 6, 13, 16, 17, 21, 24, 26.] 



Pit Thermometer. See Thermometer. [5, 6, 13, 16, 17, 21, 24.] 



Pit Water Gauge. An instrument or gauge for taking the air- 

 pressure in mines. See Gauge. [5, 13, 17, 21, 24.] 



Pitot Tube. An instrument designed to measure the velocity of 

 flow of gases, consisting essentially of two parts a tube 

 pointing up-stream and having an opening at the end facing 

 the direction of the air current, and another tube, closed at 

 the end, but with a number of small holes drilled in the 

 surface, which is parallel to the stream-lines. The open 

 ended tube determines the sum of the velocity pressure and 

 the static pressure, and the tube with closed end the static 

 pressure alone. By connecting the two tubes to a suitable 

 manometer the velocity can be determined. [4, 5, 6, 16, 

 17, 21.] 



Pivoted Moving Coil Galvanometer. See Galvanometer. [4, 10, 

 16, 19.] 



Plagiograph. A pantograph (q.v.) for drawing a copy which is 

 inclined with respect to the original figure. 



Plane Table. A drawing-board on tripod stand with sight rule 

 and trough compass, for field surveying. [2, 13, 15, 17, 20, 

 21, 24, 27.] 



Planetarium. A working model showing the planets and their 

 movements. 



Planigraph. An instrument for reducing and enlarging drawings. 

 See also Pantograph. [6, 10, 13, 15, 17, 21, 24, 25, 27.] 



Planimeter. An instrument for measuring the area of irregular 

 plane figures. [2, 5, 6, 10, 13, 15, 16, 17, 21, 24, 25, 27.] 



