FIL 
respondin'; grooves in the face of any piece 
of work, that might be to be filed, instead 
of leaving the workman at liberty to vary 
his strokes, as is necessary when a flat sur- 
face is to be produced. 
When the file is cut and finished on both 
sides, and on one or both edges, as may be 
required, it is ready for hardening, which is 
a chemical operation of some skill and inge- 
nuity. The heat is given in a furnace, where 
the work can be regularly disposed, and 
for fine, work a muffle is used. The file is first 
exposed to a low degree of ignition, which 
burns off anjj greasy or other matter, that 
might adhere to its surface. It is then dipped, 
• cold, in the grounds or thick sediment of 
beer, and while wet into a powder made of 
burned or parched horn, or leather, or other 
coally animal matter, and of common salt, 
and in this state speedily dried by exposure 
to heat. Any other mucilage which could 
be afforded at a moderate price, would pro- 
bably answer the same purpose as the beer 
grounds. The file being then put into 
the ignited muffle, smokes and soon be- 
comes red-hot, being not only defended 
from oxydation, by the covering of fused 
salt, and animal coal, which envelopes it on 
all sides, but being even rendered more 
steely upon its surface by the absorption of 
carbon. As soon as it has acquired the low 
red heat called cherry-red, it is taken out 
and plunged into pure cold water, which in- 
stantly cools it, and renders it very hard. 
There are several variations adopted in 
the hardening process by different work- 
men, by means of which they differ in their 
success. Some file-makers, as well as gun- 
smiths and locksmiths, produce the intend- 
ed effect so completely, that the whole sur- 
face of their work has a beautiful dull-grey 
aspect, every where alike ; whereas, other 
operators produce coally spots, which are 
obliged to be cleaned off. The files, when 
quite dry and clean, are slightly oiled, and 
kept in oiled paper. 
The simple operation of file-cutting seems 
to be of such easy performance, that it is 
not at ail to be wondered at that machines' 
for this purpose should have been very 
early invented. Mathurin Jousse, in “ La 
Fidelle Ouverture de l’Art de Semirier,” 
published at La Fleche, in Anjou, in 1627, 
gives a drawing and description of one, in 
which the file is draw-n along by shifts by 
wheel- work, and the blow is given by a 
hammer, which is tripped by the machinery. 
There are several in the “ Machines Ap- 
prouvees par l’Academie Royale de Pa- 
VOL. III. 
Fit 
ris;” and ode in the “American Transac- 
tions and a patent was granted a few 
years ago, for improvements in the art, to 
the editor of this work. 
The principal requisites in a machine for 
file-cutting are, that the file should be stea- 
dily supported, and the chizel adapted to 
the face without any unequal bearing. Files 
are however, for the most part, cut by 
hand; and the chief reasons are, 1. The 
cut by hand is, from its very nature, ex- 
actly of the depth the bur demands ; where- 
as; in a machine, if the stroke be not nicely 
adapted to the shift, the file may be either 
shallow-cut, or its bur may be thrown too 
close by an over heavy stroke ; and, 2. In 
machine-cut files, there must always be a 
piece left at the beginning, at each corner, 
which requires to be cut off before harden- 
ing. This may be remedied in the ma- 
chinery, but it has not yet been done. 
FILICES, ferns, one of the seven families 
or natural tribes into which the whole ve- 
getable kingdom is divided by Linnaeus, in 
his “ Philosophia Botanica.” They are de- 
fined to be plants which bear their flower and 
fruit on the back of the leaf or stalk, which 
iff this class of imperfect plants are the 
same. In the Sexual System, the ferns 
constitute the first order, or secondary di- 
vision of the twenty-fourth class, Crypto- 
gamia; in Tournefort’s Method they are 
the sixteenth class; and in Ray’s the fourth 
under the name of Capillares. Haller de- 
nominates them Epiphyllospemue, that is, 
plants that bear their seed on the back of 
the loaf; others term them Acaules, be- 
cause they have properly no stem. These 
plants in figure approacli the more perfect 
vegetables, being furnished, like .them, with 
roots and leaves. The roots creep, and ex- 
tend themselves horizontally under the earth 
throwing out a number of very slender 
fibres on all sides. The stem in these plants 
is not to be distinguished from the common 
foot-stalk, or rather middle rib of the leaves - 
so that in strict propriety the greater num- 
ber of ferns may be said to be Acaules, that 
is, to want the stem altogether: in plants 
of the second section, however, the middle 
rib, or a stalk proceeding from the root 
overtops the leaves, and forms a stem upon 
which the flowers are supported. The 
leaves proceed either singly or ia greater 
numbers from the extremities of the bran- 
ches of the main root. They are winged, 
or hand-shaped, in all the genera, except in 
adder’s-tongue, pepper-grass, and some spe- 
cies of spleen-wort. The flowers of the 
L 
