GLOSSARY. 315 



Subtense, the chord of an arc. 



Sulphates, or Sulphats, salts formed by the combination of any base 

 with sulphuric acid. 



Sulphate of copper, blue vitriol ; blue stone. 



Sulphate of iron, copperas ; green vitriol. 



Sulphate of lime, gypsum. 



Sulphate of soda, Glauber's salts. 



Sulphate of zinc, white vitriol. 



Sulphate of potash, a chemical salt, composed of sulphuric acid and 

 potash. Sulphuret of potash, sulphur and potash fused together 



Sulphate of magnesia, Epsom salts. 



Sulphuric acid, oil of vitriol ; vitriolic acid. 



Sulphurets, combinations of alkaline earths or metals, with sulphur. 



Su/amer fallows, see Fallow. 



Sum7tier yarding, stuff carted into the yard, and trodden by the cat- 

 tle, for manure. 



Super-tartrate of potash, cream of tartar. 



Swamp, a marsh, bog, or fen. 



Swamp muck, meadow mud. 



Sward, the surf ice of the ground. 



Swath, a line of grass or grain cut down by the mower. 



Swing plough, a plough without wheels. 



Table land, elevated land, of a flat or level surface. 



Tall oat-grass, see p. 229. 



Tangent, a line which touches a circle or curve, without cutting it 



Taproot, a long root, like a parsnip. 



Taprooted, having taproots. 



Tare, a weed, the common vetch or fitch, extensively cultivated for 

 its stem and leaves, as food for cattle, sheep, &c. It is one of the 

 most esteemed of the leguminous forage plants of England. 



Tares, Winter, those which are sown with Winter grain. 



Tartaric acid, the acid found in the grape. 



Tartrates, and Tartrites, salts formed by the combination of any base 

 with the acid of tartar. 



Tethering, Jx rude practice, chiefly confined to the north of Scotland, in 

 which animals are tied or chained to a particular spot, in order that 

 they may eat off all the crop within their range. 



Thermometer, an instrument to show the relative heat of bodies and 

 of the atmosphere. 



Thinner staple, (of soil,) see Staple. * 



Tillage, the preparing of land for planting and raising crops. 



Tillage crops, crops from ploughed land. 



Tillage stratum, that depth of the soil used for tillage. 



Tiller, io branch out into numerous shoots ; to send forth numerous 

 stems from the roots ; (applied to culmiferous plants only.) 



Tillered, branched out into numerous shoots. 



Till, an English provincial term, for coarse, obdurate clay. 



Tilth, the state of being tilled or prepared, for receiving seed ; the 

 degree or depth of soil turned by the plough or spade ; that avail- 

 able soil on the earth's surface, into which the roots of crops strilvQ 



Timothy, meadow cat's tail, or herdsgrass, see p. 225. 



Topping, to cut off the stalks, just above the ear. 



