642 Our Surroundings 



Sun: The large, flaming body about which revolve the earth and the 



other planets; the center of the solar system. 



Sunstroke: A dangerous condition caused by exposure to great heat. 

 Surgery: The treating of disease, deformity and injury by operation. 

 Suspension bridge : A bridge whose roadway is supported by steel cables 



strung between lofty supports. 



Sweat glands : Glands in the skin that excrete sweat. 

 Sympathetic system: Two chains of ganglia, or collections of nerves, 



located on each side of the spinal column and connected with the vital 



organs of the body, whose actions they regulate. 

 Systemic circulation: (sis-tem'ik) : The circulation of the blood 



through all parts of the body except the lungs. 



Talking motion pictures: Motion pictures in which the voices of the 

 actors and all sounds are reproduced to accompany the pictures. 



Tannin (tan'm) : An acid substance found in tea. 



Tea: A beverage containing a "stimulating substance called thein ; made 

 from dried tea leaves. 



Telegraph: An instrument for sending and receiving messages over a 

 wire by completing and breaking a charged electric circuit. 



Telegraph key: An instrument for completing and breaking the charged 

 electric circuit in a telegraph. 



Telephone: An instrument for sending and receiving the sound of the 

 human voice over a wire by means of an electric current. 



Telephotography (tel-e-fo-tog'rd-fi) : The sending of pictures by tele- 

 graph or radio. 



Telescope: An instrument for seeing distant objects clearly. 



Television (tel-e-vizh'wn) : The broadcasting and receiving of images of 

 persons or scenes by radio. 



Temperature: Degree of heat. 



Tendon: A tough band of connective tissue uniting muscle to muscle 

 or muscle to bone. 



Terrarium (te-ra'ri-wm) : A box containing earth, in which both land 

 animals and land plants are kept. 



Testa (tes'td) : The hard outer covering of a seed. 



Tetanus (tet'd-nus) : A painful and infectious disease in which some or 

 all of the voluntary muscles become rigid. When confined to the 

 lower jaw, it is called lockjaw. 



Thein (the'in) : A stimulating substance found in tea. 



Theobromine (the-6-bro'min) : A stimulating substance in chocolate 

 and cocoa. 



Theory: An explanation of some natural occurrence which many experi- 

 ments and observations seem to indicate to be true. 



Therapy (ther'd-pi) : The science which relates to remedies for disease. 



Thermal: Pertaining to heat. 



Thermometer: An instrument for measuring temperature. 



Thermostat (thur'mo-stat) : An automatic apparatus for regulating tem- 

 perature indoors. 



Thoracic duct (tho-ras'ik) : The main lymph tube of the body, extend- 

 ing along the front of the spinal column from a region just behind 

 the aorta to the left side of the neck. 



Thorax (tho'raks) : The part of the body between the neck and the 

 abdomen. 



Thunder: The sound which accompanies a flash of lightning. 



