TAC 
bern, tlie place where he was born ; a ge- 
nus of the Pentandria Monogynia class and 
Older. Natural order of Contortas. Apo- 
cin®, Jussieu, Essential character : con- 
torted ; follicles two, horizontal ; seeds im- 
mersed in pulp. There are nineteen spe- 
cies, among which we shall notice the T . 
cyniosa, cyme-flowered tabern®moiitana ; 
this is an elegant upright little tree, or 
shrub, about six feet in height ; leaves 
acute, quite entire, scarcely waved, half a 
foot long. Cymes ample, handsome, con- 
vex, axillary ; flowers without scent, dirty 
white, or reddish brown, about forty in a 
cyme ; tube of the corolla, quinquangular, 
ventricose at the base ; stamens in the en- 
larged base of the tube ; stigma margined 
at the base ; follicles oblong, very blunt, 
curved in, very large, reddish, with rust-co- 
imired spots ; one of each pair is commonly 
abortive; the pulp is orange-coloured. It> 
is found in the woods and cojrpices about 
Carthagena in New Spain, flowering An 
July and August. 
TABES dorsalis^ in medicine, a distem- 
per which, according to a late author, is a 
particular species of a consumption, the 
proximate cause of which is a debility of 
tile nerves. 
TABLE, in perspective, denotes a plaiii 
surface, supposed to be transparent, and 
perpendicular to the horizon. It is alw'ays 
imagined to be placed at a certain distance 
between the eye and the objects, for the 
objects to be represented thereon, by 
means of the visual rays passing from every 
point thereof through tlie table to the eye ; 
whence it is called perspective-plane. 
Tabi,e, among the jewellers. A table- 
diamond, or other precious stone, is that 
whose upper surface is quite flat, and only 
the sides cut in angles ; in which sense a 
diamond, cut table-wise, is used in opposi- 
tion to- a rose-diamond. 
Table is also used for an itidex or repef- 
tory, put at the beginning or end of a book 
to direct the reader to any passage he may 
have occasion for; tlius we say, table of 
matters, table of authors quoted, &c. Ta- 
bles of the Bible are called concordances. 
Table, in mathematics, system of num- 
bers calculated to be ready at hand for the 
expediting astronomical, geometrical, and 
other operations : thus we say, tables of the 
stars ; tables of sines, tangeiits, and secants ; 
tables of logarithms, rhumbs, &c. ; sexage- 
nary tables ; loxodromic tables &c. 
TA CCA, ill botany, a genus of the Hex- 
andiia Mouogynia class and order., Natu- 
TAC 
ral order of Coronarim. Narcissi, Jussie®. 
Essential character : calyx six parted ; co- 
rolla six-petalled, inserted into the calyx, 
anther bearing ; stigma stellate ; berry dry, 
hexangular, many-seeded, infeiior. There 
is only one species, viz. T. piniiatifida ; the 
root of w'hich is tubei'ous, composed of 
many tubers heaped together, here and 
there emitting fibres ; radical leaf siibsoli- 
tary, petioled, ternate, or biternate ; leaf- 
lets laciniate pinnatified, acute, spreading, 
decurrent a little along the sides of the pe- 
tiole, a foot in length ; scape half a fathom 
in height, herbaceous, fistular, grooved to- 
wards the top, erect ; umbel terminating, 
sessile; peduncles four to eight; anthers 
twelve, on short filaments ; germs three, 
or one three-lobed ; styles three, short : 
stigma obcordate, two-lobed ; berry black ; 
seeds brown. It is a native of the East In- 
dies, China, Cochin China, Banda, and the 
Society Isles. 
TACK, in a ship, a great rope having a 
wale-knot at one end, which is seized or 
fastened into the clew of the sail; so is reef- 
ed first through the chesse-trees, and then 
is brought through a hole in the ship’s side. 
Its use is to carry forward the clew of the 
sail, and to make it stand close by a wind : 
and whenever the sails are thus trimmed, 
tlie main-tack, the fore-tack, and mizen- 
lack, are brought close by the board, and 
haled as much forward on as they can be. 
The bowlings also are so on the weather-side; 
the iee-sheets are haled close aft, and the 
lee-braces of all the sails are likewise braced 
aft. Hence they say, a ship sails or stands 
close upon a tack, i. e. close by the wind. 
The w'ords of command are, hale aboard 
the tacks, i. e. bring tlie tack down close to 
the chesse-trees. Ease the tack, i. e. slack- 
en it, or let it go, or run out. Let rise the 
tack, i. e. let all go out. 
The tacks of a ship are usually belayed 
to the bitts, or else there is a chevil on pur- 
pose to fasten them. 
Tack about, in the sea-language, is to 
turn the sliip about, or bring lier head 
about, so as to lie the contrary way. In 
order to explain tlie theory of tacking a 
ship, it may be necessary to premise a 
kitown axiom in natural philosophy, “ that 
every body will persevere in a state of rest, 
or of moving uniformly in a right line, un- 
less it be compelled to change its state by 
forces impressed, and tliat tire clrange of 
motion is proportional to the moving force 
impressed, and is made according to the 
light line in v.hich that force k exerted.” 
