CLASS I. NUTRITIOUS ROOTS. 357 



last for this purpose is to be preferred ; but one third part of tan, 

 mixed with two thirds of manure, makes a heat less violent, and 

 more durable than manure alone. 



A frame six feet square is composed of four boards; the front 

 board a foot deep ; the back or north board eighteen inches. This 

 frame is covered with two sashes, formed of small, cheap glass, five 

 by seven inches. The sashes may be provided with hinges on the 

 back side, for the purpose of raising the front and giving air occa- 

 sionally. The surface of the earth, as Mr. Knight has recommended, 

 should be inclined towards the horizon in an angle of 15 degrees. 

 Prepare, therefore, the surface of the earth by sinking the front only 

 to the required depth, and of a width and length exceeding that of 

 the frame. The manure from the stable is now to be built up on 

 this foundation by placing successive layers of manure, with a fork, 

 to the height of about fourteen of fifteen inches, and pressed or 

 trodden gently throughout, its surface corresponding in its inclina- 

 tion with its earthy foundation ; the dimensions six inches wider on 

 every side than the frame. On this the frame is placed, and cov- 

 ered with the sashes, and in about two or three days, if the weather 

 is pleasant, cover the surface with rich loam from seven to twelve 

 inches deep, and again put on the lights. If the excess of heat and 

 fermentation is too great, raise the glasses a little in front, and when 

 the earth is of the right temperature, or in about ten days from the 

 commencement, plant your early cucumber, radishes, lettuce, cab- 

 bages, &c. &c. ; and as these increase in size, they may be trans- 

 planted either to the open ground or into other hot-beds, and 

 allowed more space, and thence to the open field. In cold, wet 

 weather, the sides may be protected by straw or litter placed around 

 them; and the heat may be renewed by cutting down square the 

 outside, and piling fresh manure around the sides and the frame. 

 The hot-bed should be prepared in March, and made ready by the 

 end of winter. 



CLASS I. NUTRITIOUS ROOTS. 



1. ARACHIS HYPOG-EA, or GROUND NUT. 



An annual plant, with long, trailing stalks. A native of Mexico, 

 but now cultivated in the West Indies for its nuts, which are oblong, 

 and grow beneath the surface. These are used by the negroes as 

 food. But in France they are now cultivated for the abundance of 

 the oil they produce. This is said to be equally as valuable, for the 

 table and other purposes, as the oil of olives, and superior to that 

 for burning. A bushel of the nuts produces by cold expression a 

 gallon of oil ; but more may be produced by heat, but of a quality 

 inferior. 



2. ARRACACHA, of the order of Umbdliferce. 



A plant from South America, which some have supposed may 

 supersede the potato. Its main root divides into four or five large 



