35o] F U R gree of cleanliness which cannot be attuned where grates and - . of the common construction employed. The design of this contrivance is to prevent the heat, generated and thrown out into any mom or apartment by combustion", from being unnecessarily Wasted by the air of such room being made to maintain the combustion of the fuel in the grate. To effect this purpose, the air supporting the fire in the grates or stoves mad.- with the patentee's improvements, or in other grates to which they may be applied, ought to be conveyed through a tube (which he calls an air-tube) from the outside of the house : or it may be made to pass from the outside of the house be- tween the joists, so as to be brought to the bottom bars of the grate, without communicating with the interior air of the room ; while the grates, and other parts connected with them, should be so construct- ed, that the passage may be closed in a greater or less degree by means of a valve, small door, cock, or any similar contrivance, whenever it is not requisite to supply the tire w ith cold air from the outside of the house : or,. the same object may be attained by directing die tube to a cellar, larder, &c. which wi_l thus be thoroughly ventilated, and pre- vented from acquiring unhealthy or disagreeable smells. — As our limits will not permit us to spe- cify the constituent parts of Mr. Burns's design, we reft i the re id r to the 12th vol, of the Repertory, &c. above quoted, where it is mi- nutely des< ribed, and farther illus- trated by two plates. But we can- not conclude the subject, without ', thai his improvements are amtm< d to be an effectual cure for imdk) durante* j and vlku afire tui hted in grates of the patenteeV construction', it bums up, and be- comes lively in a few minutes, without the aid of bellows, and that watchful care which common stoVeS or grates require. — See also Boilers, and Fire-place. FURROW, in agriculture, a term not properly defined, as it has three or four distinct significa- tions, namely, 1. The soil turned! up by the plough ; 2. The trench left by this operation j 3. The in- terval between two ridges ; and, 4. The cross drain which receives the. rain-water collected by these intervals.— Dr Johxson adds a fifth, bnt he obviously mistakes furrow for drill. According to Mr. Marshall, there are three ideas which lay claim to the word furrow : — ; 1 . The trench made by the plough, which may be called a plough' furrow ; 2. The collateral drains, or an inter-furrow j and 3. The transverse drains, or the cross* furrow. The proper formation and dis- position of furrows, is an object of the first importance in tillage, to effect the complete draining of water. Hence, in plain fields, the rain-furrows ought to be drawn according to the declivity of the land; but, in rising grounds it wilt be most proper to direct them to that side which slightly deviates from the horizontal line. It also deserves to be remarked, that in all situations where it is practicable, especially at the decli- vities of fields, reservoirs or pits should be dug, or formed, in order to collect the drained water, toge- ther with the finest particles oJ earth) mire, and other ingredients of Manure: after the Mater has subsided, these valuable materials might
