FOR 



FOU 



to produce bottom heat ; they are 

 used like frames, and in every re- 

 spect resemble them in effect. The 

 following is a description of the pit 

 of one of the Enplisii gardens : " It is 

 four feet deep witliiii ; the lowest ten 

 inches of solid brick-work sunk in the 

 earth ; the remainder is a flue, three 

 inches wide in tlie clear, carried en- 

 tirely round the pit ; the inner wall 

 of which, forming the sides of the pit, 

 is four-inch work, well bedded in 

 mortar, and pointed, to prevent the 

 steam penetrating ; the outer wall of 

 the flue is also four-inch, but open- 

 work, to admit the steam and that of 

 dung coatings into the flue, the top 

 of which is rendered tight by a cov- 

 ering of tiles, &c. The frame rests 

 on the external wall of the flue. The 

 cavity of the pit, which is kept dry 

 by means of drains, is nine feet two 

 inches long, two feet eight inches 

 wide, and four feet deep. It is filled 

 with broken bricks to within eighteen 

 inches of the top ; then a foot of 

 short cold dung, six inches of very 

 rotten dung, trod down so as to ad- 

 mit half an inch depth of coal ashes, 

 for preventing the intrusion of any 

 worms that may be in the dung, com- 

 plete the structure." See Frame. 



FORCING PUMP. See Pump. 



FOREST. A natural collection of 

 trees. The principal trees are men- 

 tioned under their respective heads. 



FOREST FLIES. Flies of the 

 genus Hippobosca. 



FORFICULA. The genus of in- 

 sects to which the earwig belongs. 



FORGE. " The workshop in 

 which iron is hammered and shaped 

 by the aid of heat. The term is gen- 

 erally applied to the places in which 

 these operations are carried on upon 

 the comparatively small scale ; the 

 great workshops in which iron is 

 made malleable for general purposes 

 being called shingling mills. A com- 

 mon forge consists of the hearth or 

 fire-place, which is merely a cavity in 

 masonry or brick- work well lined w ith 

 fine clay or brick, upon which the ig- 

 nited fuel is placed, and upon the 

 back or side of which a powerful blast 

 of air is driven in through the nozzle 

 30G 



of a double-blasted bellows, which, in 

 a common forge, is generally worked 

 by a hand lever. Forges are some- 

 times constructed so as to be porta- 

 ble, when the bellows is most con- 

 veniently placed under the hearth : 

 these are used in ships, and for vari- 

 ous jobs on railways, &c." — (Brandc.) 



F O R K. The dung and dismng 

 fork is in the form of a spade, with 

 three or more flat prongs : it is em- 

 ployed in loose soils much more ex- 

 peditiously than the spade in garden 

 tillage. The hay, or pitch-fork, for 

 turning hay, grass, or manure, is fur- 

 nished with a long handle and two 

 roundish teeth : sometimes a forked 

 branch is used. 



FORMATION. In geology, a 

 group of deposites or strata apparent- 

 ly referable to a common origin or 

 period. 



FORMICA. The genus of ants, 

 now the tvpe of a tribe, the Formindce. 



FORMIC ACID. The fluid eject- 

 ed by ants when irritated contains 

 this acid. The acid is formed by dis- 

 tilling tartaric acid with sulphuric 

 acid and peroxide of manganese, and 

 consists of Cn HOa-fHO. It is high- 

 ly corrosive, acid, and of a peculiar 

 odour ; combines with bases to form 

 formiales, which are very soluble. 

 Formic acid contains a compound 

 radical formyl (Cj H). 



FORMULA. In chemistry, the ex- 

 pression, by symbols, of the composi- 

 tion of any substance, as (EO, FOO3) 

 {or formic ether. 



FOSSA. In zoology, a depression 

 on a bone. 



FOSSIL. A part or the whole of 

 any animal or plant imbedded in the 

 earth, and more or less converted 

 into stony matter. 



FOSSORES. A group of hymen- 

 opterous insects, which dig or exca- 

 vate cells m wood or earth to depos- 

 ite their eggs. 



FOSSORIAL (from fodio, I dig). 

 Animals which dig their holes, as 

 moles. 



FOUNDATION. In architecture, 

 the lower part of a wall, on which the 

 wall is raised, and always of much 

 greater thickness than such wall. A 



