312 GLOSSARY. 



Prolate, extended beyond an exact round. 



Pnlverization, breaking up into small portions ; reducing to powder. 



Pulverulent, dusty ; consisting of fine powder ; having power to dis- 

 engage adhesive particles of soil ; addicted to lying and rolling in 

 the dust, as fowls. 



Pyrites, sulphuret of iron or copper ; a union of sulphur and iron, or 

 sulphur and cgpper. 



Pyroligneous, or PyroUgnic, acid, an acid obtained from wood, by 

 distillation. 



Quackgrass, witchgrass, sometimes called dog-grass ; a perennial 

 grass not easily eradicated from ploughed grounds. 



Quadrennial, occurring once in four years. 



Quartz, one of the hardest minerals known. It sometimes occurs in 

 minute grains, and sometimes forms mountain masses. It gives 

 plentiful sparks with steel, and is easily broken with a smart stroke 

 of a hammer, it has a vitreous or glassy lustre, and is sometimes 

 as transparent as glass. Rock crystal and flint are varieties of 

 quartz. It is the hardest ingredient in granite. 



Quincunx, see p. 283. 



Radicles, horizontal roots of plants ; those parts of the seeds of a plant, 

 which, on its vegetation, become its roots. 



Radius, the half diameter of a circle ; the distance from the centre of 

 a circle to its circumference. 



Rape, or coleseed, cultivated for the oil expressed from the seeds. 



Rationale, an explanation. 



Ration, a certain allowance or share, of food or provisions. 



Rayolt, or Rayoled, (a German term,) trench ploughed. 



Resinous trees, trees which contain resin, as the pine, &c. 



Ribgrass, Ribwort, or Ribwort plantain, see Plantain. 



Ridge, the ground thrown up by the plough. 



Right-aJigle, an angle having one of its sides perpendicular to another. 

 The angles of a square, or parallelogram, are right-angles. 



Right-angled-triangle, a triangle containing one right-angle. If a 

 square, or parallelogram, be divided into two equal parts, by an 

 oblique line, drawn from one corner to the opposite one, each part 

 will form a right-angled-triangle, because the angle formed by the 

 two sides of the original figure is a right-angle. 



Right line, a straight line ; the shortest distance between two points. 



Rix dollar, a silver coin, having different values in different countries. 

 In Prussia, (referred to on p. 24,) it is worth about 68 cts ; in Ba- 

 varia, about 94 cts ; in Saxony, about 95 cts ; in Denmark and Hol- 

 land, about $'1.00 ; in Sweden, about $1.04 ; and in Hamburg, 

 about $1.06. 



Root Crops, potatoes, turnips, beets, carrots, &c., which divide and 

 pulverize the soil by their roots, and keep it clean from weeds. 

 These are called ameliorating crops. 



Rough stalked meadow grass, the Poa trivialis. 



Rowen, see Aftermath. 



Ruta Baga, Swedish turnip. 



Sainfoin, or Saintfoin, a plant, cultivated for fodder ; the Hedysarum 

 onobrychis, or cock's head. 



Sal, a salt. 



