HEAT. 71 



Check. — The forsaking, by a hawk, of its proper game, to follow 



otlier birds. 

 Clap. — The nether part of the beak of a hawk. 

 Hooding, — The blinding of a hawk by means of a hood. 

 Leash. — A leather thong by which the falconer holds the hawk. 

 Lure. — An object, not unlike a fowl, held out by the falconer 



to call a hawk, 

 ftuarry. — The hawk's prey. 

 Ruf terhood. — A hood to be worn by a hawk when she is first 



drawn. 

 Seel'ing' (Fr. dller^ to wink). — The running of a thread through 



the eyelids of a hawk when first taken, so that she may 



see verj^ little, or not at all; to make her the better endure 



the hood. 



HEAT. 



Th.ermot'ics, or Pyronomics (Gr. therme, heat, pur, fire, and 

 nomas, a law). — The doctrine or the science of heat. 



Absorption, — The process or act by which heat is made pas- 

 sively to disappear in some other substance, through 

 molecular or other invisible means. 



Actinom'eter, — An instrument for measuring the intensity of 

 heat in the sun's rays. 



Cerau'nics (Gr. Iceraunos, thunder and lightning). — That 

 branch of natural philosophy which relates to the efitict of 

 heat and electricity. 



Interfe'rence, — The mutual action of two intersecting pencils 

 of radiant heat, by which, like two interfering pencils of 

 light, they increase each other's effects at certain points, 

 and diminish or destroy them at others. 



Pyrol'ogy (Gr. jmr, fire, and logos, a discourse). — The natu- 

 nd lilstory of heat, or a treatise on the subject. 



Pyrom'etry (Gr. pur, fire, and metreo, I measure). — The 

 art of measuring degrees of heat, or the expansion of bodies 

 by heat. 



Radia'tion, — The divergence or shooting forth of heat from a 

 point or surface. 



Th.ermoch'rosy (Gr. therme, heat, and chrosis, coloring). — 

 The property possessed by heat of being composed, like 

 light, of rays of difierent degrees of refrangibility, which 

 are unequal in rate or degree of transmission through 

 diathermic substances. 



