THR 



THY 



THORAX. The chest. The cav- 



ty of the chest is tennod the tliora- 



eic cavity, and contains the heart and 



lungs. In entomology, the second 



segment of the frame. 



THOIIX. The genus Cratagus: 

 thorny shruhs of the family Rosacea. 

 The C. oxyacantha is the .May, or Eng- 

 lish hedge thorn. The C. cms galli, 

 or Newcastle thorn, is much used in 

 Delaware as a hedge ; it is supposed 

 to be supeiior to the C. cordata, or 

 Virginian thorn. 



THORN-APPLE. The stramo- 

 nium. 



THRASHING AND THRASH- 

 ER.S. " The separation of the grain 

 from the ear in corn has always been 

 one of the most laborious operations 

 on a farm. 



" WTiere the grain is thrashed out 

 immediately after harvest, to be put 

 into a granary, the most common 

 practice is to level a portion of a lield, 

 and laying the gram in the straw in a 

 large circle, to drive oxen and horses 

 over it till it is all trodden out. Till 

 ingenuity had produced machines to 

 supersede the flail, this was tiie only 

 instrument in use. The first idea of 

 a machine lor thrashing was that of 

 imitating the motion of the flail, hut 

 so much depends on the eye of the 

 thrasher, that no mechanism could 

 well miitate the motion of his arms. 

 This was consequently given up, and 

 an imitation of the rubbing of the 

 grains from the ears between the 

 hands, combined with the heaters 

 of a flax- dressing machine, grad- 

 ually produced the present improved 

 thrashing machine. 



" Without a figure it would be dif- 

 ficult to describe the ditTerent parts 

 and motions of a thrashing machine. 

 They are, however, now so common, 

 that it will suffice to give the general 

 principal of action, and to mention 

 some of the latest improvements in 

 it. A rapid motion is given to a hol- 

 low cylinder round a horizontal axis ; 

 on the outer surface there are pro- 

 jecting ribs parallel to the axis at 

 equal distances from each other, 

 or, what is more common, spikes. 

 Around half the cylinder is a case, 

 794 



the inner surface of which is lined 

 with plates of cast-iron grooved in 

 the direction of the axis, or furnished 

 with spikes. The ribs or beaters 

 come quite close to these, so that an 

 ear of wheat or other grain cannot 

 well pass between them without be- 

 ing flattened. The sheaves of grain, 

 liaving been untied, arc spread on a 

 slanting table, and in some machines 

 are drawn in by the spikes. The 

 motion of the cylinder or drum is 

 very rapid. The beaters act on the 

 straw as it comes through, and beat 

 out most of the grain ; but what re- 

 mains is carried in between the beat- 

 ers and the case, and when it has 

 made half a revolution all the grain 

 has been beaten and rubbed out. It 

 falls on a sieve, which lets the grain 

 through, but retains the straw, which 



j is raked off by hand, or by circular 

 rakes moved by the machinery. The 

 great perfection of a thrashing ma- 

 chine is to rub out every grain and 

 to break the straw as little as possi- 

 ble ; the larger the scale of the ma- 

 chine the better it does this. Hand 

 machines have been made on the 

 same principle, but they do not effect 

 any saving in the expense, requiring 



' many men to produce the effect of 

 one horse. Moveable thrashing ma- 

 chines are very generally in use where 

 farms are small. They are often the 

 property of an industrious mechan- 

 ic, who undertakes to superintend 

 the work, the farmer finding horses 

 and men. Thus he goes from farm 



j to farm. The best machines will 

 thrash 25 to 50 bushels the hour." 

 The thrashers best known are Pitt's, 

 Hall's, Hale's, Whitman's, Stafford's, 



1 Warren's, Bostwick"s. 



I THREAVE. Twelve sheaves of 



! grain in the straw. 



THROAT. Faux, the commence- 

 ment of the tube of a personate or 

 labiate flower. 



i THRIPS. The genus of vine fret- 

 ters, minute flies which destroy the 

 buds, leaves, and flowers of several 

 fruit-trees. They are extremely act- 

 tive, and skip considerable distances. 

 See Insects. 

 THYME. The genus Thymus, ol 



