Glossary 643 



Thyroid glands (thi'roid) : A pair of ductless glands located on each 

 side of the esophagus just below the larynx. Their secretions are nec- 

 essary to the proper nutrition of the body. 



Tides: The regular rise and fall of the ocean every 12 hours and 26 

 minutes, caused by the attraction of the moon and, to a lesser extent, 

 of the sun. When sun and moon pull together, we have extremely 

 high, or spring, tides, and when they pull at right angles to each other 

 we have low, or neap, tides. A rising tide is called a flood tide, a 

 falling tide an ebb tide. 



Time belt: A belt or territory in which the standard time of all places 

 _ is the same. There are four standard time belts in the United States. 



Tissue: A collection of cells joined together, which do a special work. 



Tonsils: Two fleshy tissues lying at the back of the mouth. 



Tornado (tpr-na'do) : An exceedingly violent, whirling wind storm 

 accompanied by thunder, lightning and rain; travels a short distance 

 over a narrow path. 



Toxin: A poison produced by the action of bacteria upon organic matter. 



Toxin-antitoxin: A mixture which when introduced into the system 

 prevents certain diseases by counteracting the effect of toxins. 



Trachea (tra'ke-a) : The tube in the body through which animals get 

 air; the windpipe. 



Trade winds : Wind currents flowing southwest and northwest from the 

 tropical belts toward the heat equator. 



Transformer: A device for increasing or decreasing the voltage, or 

 pressure, of an alternating electric current. 



Translucent (trans-lu's<?nt) : Permitting the passage of light but not 

 vision. 



Transmitter: That part of a telegraph or telephone by means of which 

 messages are sent. 



Transparent: Permitting the passage of light and vision. 



Transpiration (tran-spi-ra'shwn) : Giving off of water vapor by the 

 leaves of plants. 



Trap : A bend in a drain pipe to hold water and thus seal the pipe against 

 sewer gas. 



Triceps (tri'seps) : The muscle of the upper arm that extends the fore- 

 arm. 



Triplane: An airplane with three pairs of wings, one above another. 



Tropic of Cancer: An imaginary line around the earth parallel to the 

 equator and 23 l / 2 degrees north of it. 



Tropic of Capricorn: An imaginary line around the earth parallel to 

 the equator and 23^ degrees south of it. 



Truss bridge : A bridge built in the form of an open framework of 

 wood or metal. 



Trypsin (trip'sln) : A ferment in pancreatic juice which changes albu- 

 mins to soluble form. 



Tsetse fly (tset'se) : An African fly whose bite usually causes sleeping 

 sickness by introducing a parasite into the body. 



Tuberculosis (tu-bur-ku-16'sis) : An infectious, wasting disease. 



Tungsten (tung'st<?n) : A grayish-white metal. One of the elements. 

 It is largely used as the filament in bulbs for incandescent lighting. 



Tuning: Adjusting a radio to receive waves from a sending station. 

 Adjusting a musical instrument to the proper pitch. 



Tuning fork: A forked piece of steel which vibrates at a given rate 

 when struck, producing a certain fixed tone or note. Used in tuning 

 musical instruments. 



