FOA 



FOD 



acid, and has been recommended as 

 a manure. 



FLUTINGS. The grooves of col- 

 umns. 



FLUVIALES. A tribe of water 

 plants, of endogenous .structure, near- 

 ly resembling sea-wccds. Sea wrack 

 (Zostera marina) is used, when dry, 

 10 stuff cushions and for packing. 



FLUX. In chemistry, substances 

 which arc in themselves very fusible, 

 or which promote the fusion of other 

 bodies. When cream of tartar is de- 

 flagrated with half its weight of nitre, 

 a mixture of charcoal and carbonate 

 of potash remains, which is often call- 

 ed black flux : when an equal weight 

 of nitre is used, the whole of tlie char- 

 coal is burned off, and carbonate of 

 potassa remains, which, when thus 

 procured, is called white flux. 



Flux, in diseases, any unusually in- 

 creased discharge, as diarrhoea. 



FLY. In agriculture, any winged 

 insect injurious to crops, as the tur- 

 nip, wheat, Hessian fly, <kc., for 

 which see the plants respectively. 



Fly. In machinery, an appendage 

 given to machines for the purpose of 

 regulating and equalizing the motion, 

 as in the windlass, jack, pile engine, 

 &c. ; and sometimes for collecting 

 force in order to produce a very great 

 instantaneous impression, as in a 

 coining press. Generally it is form- 

 ed of a heavy disk or hoop, attached 

 to the axis ; sometimes of heavy 

 knobs at the extremities of a bar hav- 

 ing the same position. The fly is of 

 great use in all cases where the pow- 

 er or the resistance acts unequally 

 in the different parts of a revolution. 



FLYING BUTTRESS. A beau- 

 tiful and useful portion of a Goth- 

 ic structure, consisting of arches 

 thrown off from a mass of masonry 

 against a wall, to support it from 

 pressure acting from above, as by the 

 roof 



FLY POWDER. Black suboxide 

 of arsenic, used to kill flies, but dan- 

 gerous, from its poisonous nature. 



FOAL. A young horse. 



FOALING. The act of parturi- 

 tion or bringing forth young in the 

 mare. Good feeding and moderate 

 300 



exercise are found to be the best pre- 

 ventives against slinking, which is 

 most prevalent when half the time 

 of pregnancy has elapsed. If a mare 

 has been regularly exercised, and ap- 

 parently in health while she was in 

 foal, little danger will attend the act 

 of parturition. If there be false pres- 

 entations of the foetus, or difficulty 

 in producing it, it will be better to 

 have recourse to a well-informed 

 doctor, rather than injure the mother 

 by the violent and injurious attempts 

 which are often made to relieve the 

 animal. As soon as the mare has 

 foaled, she should be turned into 

 some well -sheltered pasture, with a 

 hovel or shed to run into when she 

 pleases ; and as, supposing she has 

 foaled in April, the grass is scanty, 

 she should have a couple of feeds of 

 corn daily. The mare may be put to 

 moderate work a month after foaling. 



FOCAL DISTANCE. In optic.«, 

 the distance between the centre of a 

 lens or mirror and the point into 

 which the rays are collected. 



FOCUS. A point where heat, light, 

 sound, &c., are collected, either by the 

 action of glass or reflecting surfaces. 

 In geometry, certain points in the 

 curves, called conic sections, which 

 are also foci for radiant emanations. 



FODDERS. All substances used 

 as food for animals. In some parts 

 of tlie United States it is, however, 

 confined to the leaves stripped from 

 corn. Coarse fodders are those which 

 resemble straw, 6cc., occupying much 

 bulk. 



The comparative value of fodders is 

 a prime question in husbandry, and 

 which can hardly have been said to 

 assume a trustworthy estimate until 

 recently, when careful experiments 

 have been made by Thaer, Raumer, 

 Block, and Boussingault. In the an- 

 nexed table, by the latter, are shown 

 the results obtained by chemical ex- 

 amination and practical feeding. In 

 the first, the amount of nitrogen in 

 100 parts is found, which gives the 

 quantity of fibrin, albumen, and ca- 

 sein, by multiplying by 63 ; thus, in 

 the talile, the nitrogen in good hay is 

 1-34 per cent., which is equivalent to 



