39»] GRA the insect attains its full growth, after having four times changed its coat daring the summer. Grasshoppers do not abound in Britain, and indeed are seldom s; en in any considerable numbers, on account of.our variable climate. But, in the warmer countries of Asia, Africa, and Europe, espe- cially in Spain, they commit incal- culable damage, by destroying the whole vegetation of a eorn-lield, in a short period of time. — The only method of extirpating these preda- tory vermin, hitherto known, is to destroy their eggs wherever they can be discovered in the ground, either in early spring or late au- tumn ; for, a-> they multiply ra- pidly, the extermination of the winged insects alone would not be attended with the desired effect. — For this purpose, ditches two or three feet deep, may be formed in autumn, filled with horse-dung, to which they are extremely partial, and the surface covered with a few inches of mould. In the following spring, numerous families of grass- lioppers, with their eggs, will be found assembled in these ditches, where they may be readily de- stroy ed. — See also Locust. GRASSWRACK, or 'Austin, I., a perennial native plant, of two
- •)! t'u s, the principal of which is
the marina, or Sca-grasswrack, found on sea-shores, and in salt- r ditches near Yarmouth. Tins < getable grows at the bot- tom < t >!.'■ 01 ' an, as common as ,., mo ' - dun e in woods : ii is tl.iown on shore by the tide in such abundance, that mounds or dams, d with its assistance, to pn ■ it the i i;i ion hnu ni of the The green leaves are said to be an useful and durable substitute GRA for thatch : when exposed to the air and weather, they become white. — The inhabitants of Goth- land, employ the grasswraek as an excellent manure, and likewise for stuffing their beds, as it is softer than hay or straw. — Horses and swine eat this herb, but it is not relished by cows, unless mixed with hay. — The ashes obtained from the whole plant are, with great advantage, employed by the Germans, in the manufacture of glass. GRATES for Firf.s, are com- posed of ribs of iron, placed at small distances from each other, so that the air may pass through the fuel, and the accumulation of ashed be, as much as possible, pre- vented . Grates are peculiarly adapted to the use of pit-coal, which requires a greater draught of air to promote its burning freely, than any other kind of fuel. In the year 1/()1, a patent was granted toAIr.Bnx.i amin Ch mills Collin.s, of Salisbury, WiltSj for a grate on a new construction, to be used either in or out of a chim- in v. This invention is said to.be calculated to increase the adtion of the air upon fire, by augmenting and directing the passage of the former through the latter. Thus the fire may be rendered so in- tense as to present a perfect white heat; and, as the draught of air is very great, the patentee observes, that " all, or nearly all of the im- ignited smoke is carried down into the lire and there consumed, in- stead of passing off in the common way." To effect this purpose, he. cun.strucfs one or more air-flues provided with stops, by which he may at pleasure promote the
- " draught
