175 



a clock for observing the time of transit of a heavenly body 



over the meridian of a place. [2, 3, 10, 11, 13, 15, 17, 21, 



25, 26. 27.] 



Transit Photograph Apparatus. A device for moving the photo- 

 graphic plate instead of the telescope to allow for the rotation 



of the earth in star photography. [11.] 

 Transit, Prime Vertical. A transit instrument, the telescope of 



which revolves in the plane of the prime vertical. Used for 



observing the transit of stars over the circle. [21, 25.] 

 Transit Theodolite. See Theodolite. [2, 5, 13, 15, 16, 17, 20, 21, 



24, 25, 26, 27.] 

 Transmitter. Tn the telephone, the funnel for receiving the 



voice and conveying the waves of sound upon the thin iron 



diaphragm. [16.] 



Traver's Sight-Rule. See Sight-Rule. [13, 15, 27.] 

 Trechometer. A kind of odometer (q.v.) or contrivance for 



ascertaining the distance run by vehicles. [21.] 

 Trestles for Drawing-Boards. Drawing office equipment. [2, 



15, 17, 20, 21, 24, 27.] 

 Trial Frame. A spectacle frame into which trial lenses can be 



placed for testing sight. [2, 17, 20, 21, 26.] 

 Trial Sight Case. A case of spectacle lenses for testing the sight. 



[2, 17, 20, 21, 26.] 

 Triangular Beam Compass. See Beam Compass. [2, 13, 15, 17, 



20, 21, 26, 27.] 



Triangular Compasses. See Compasses. [2, 5, 13, 15, 16, 17, 20, 



21, 24, 26, 27, 28.] 



Triangular Scales. Drawing scales triangular in section, con- 

 taining scales on each of the three sides. [2, 5, 13, 15, 17, 



20, 21, 24, 26, 27.] 

 Tribometer. An instrument resembling a sled, used in estimating 



the friction of rubbing surfaces. 

 Tribrach, Quicksetting. A special form of mounting for engineer's 



field instruments, designed to save time in setting up. [13, 



15, 21, 24, 25, 26, 27.] 

 Trichinascope. An apparatus for the detection of trichinae in 



the flesh of animals, as of swine. [2.] 

 Triple Aplanat Magnifier. See Magnifier. [1, 2, 3, 12, 13, 15, 



23, 26.] 

 Triple Nib Drawing-Pen. A drawing-pen for ruling a heavy or 



broad line. [2, 13, 15, 27.] 

 Trocheameter. A revolution-counter (q.v.), for fixing to the 



wheel of a vehicle. [4, 5, 13, 15, 16, 17, 19, 21, 24, 25, 26.] 

 Trochometer. An instrument for computing the revolutions of 



a wheel ; an odometer (q.v.). [13.] 

 Tromometer. An instrument for measuring earth tremors. See 



also Seismograph. [21.] 

 Trough Compass. A compact form of magnetic compass used 



where the magnetic north and south only is required. 



