T I A 
TIL 
T 1 L 
79 5 
into a hard black enamel. With borax it 
exhibits the same phenomena, or even when 
the stone is simply heated at the end of a 
pincer. 
^ A specimen of thummerstono, analysed by 
Klaproth, contained 
52.7 silica 
25.6 alumina 
9-4 lime 
9-6 oxide of iron, with adrace 
of manganese. 
97.3 
A specimen, analysed by Vauqueliu, con- 
tained 44 silica 
13 alumina 
19 lime 
14 oxide of iron 
4 oxide of manganese 
99. 
THUNDER. See Electricity. 
THUNBERGIA, a genus of plants be- 
longing to the class and order didynamia 
angiospermia. The calyx is double ; the 
corolla bell-shaped ; capsules beaked. There 
are 2 species. 
THUS. See Resins. 
THYMBRA, a genus of the class and 
order didynamia angiospermia. The calyx 
is two-lipped ; seeds semibifid. There are 
3 species. 
THYMUS, Thyme, a genus of plants of 
the class didynamia, and order gymnosper- 
nfia ; and in the natural system ranging under 
the 42d order, verticillatac. The calyx is bi- 
labiate,, and its throat closed with soft hairs. 
There are 22 species ; of which only two are 
natives ot Britain, the serpyllum and acinas. 
]. The serpyllum, or mother of thyme, has 
pale red flowers growing on round heads, 
terminal; the stalks are procumbent, and the 
leaves plane, obtuse, and ciliated at the base. 
5. The acinas, or wild basil, has flowers grow- 
ing in whorls on single footstalks ; the stalks 
are erect and branched ; the leaves acute and 
serrated. The thymus vulgaris, or garden 
thyme, is a native of France, Spain, and 
Italy. The attachment of bees to this and 
other aromatic plants is well known. In the 
experiments made at Upsal, sheep and goats 
were observed to eat it, and swine to refuse 
it. 
Thymus, in anatomy, a gland, which in 
infants is very remarkable ; it is situated in 
the upper part of the thorax, immediately 
under the sternum, and lies upon the peri- 
cardium, and on the trunk of the aorta and 
of the vena cava. See Anatomy. 
THYNNUS, a genus of the hymenoptera 
order of insects. The generic character is, 
mouth horny, with an incurved inaudible ; 
the jaw short and straight ; lip longer than 
the jaw, membranaceous at the tip, and trifid, 
the middle divison emarginate ; tongue very 
short, involute ; feelers four, equal, filiform ; 
antennas cylindrical, the first joint thicker. 
There are four species, three inhabiting New 
Holland, and the fourth is found in Africa. 
THYROID GLAND. See Anatomy. 
THYRSUS, in botany, a mode of flower- 
ing resembling the cone of a pine. 
TIARELLA, a genus of plants of the class 
deeandria, and order digynia, and in the na- 
tural system ranging under the 13th order, 
succulent*. The calyx is quinquepartite ; 
the corolla pentapetalous, and inserted into 
the calyx; the petals are entire ; tfie capsule 
is unilocular and bivalve, one valve being 
less than the other. There are two species, 
the cordifolia and trifoliata, natives of North 
America. 
TIBIA. See Anatomy. 
TIBIALIS, or Tibiasus. See Anatomy. 
TIDES. See Astronomy. 
Tide-waiters, or tide-men, are inferior 
officers belonging to the custom-house, whose 
employment it is to watch or attend upon 
ships, until the customs are paid ; they get 
this name from going on board ships on their 
arrival in the mouth of the Thames or other 
port, and so coming up with the tide. 
TIERCE, orTEiRCE, a measure of liquid 
things, as wine, oil, &c. containing the third 
part of a pipe, or forty-two gallons. See 
Measure. 
TIGER. See Feus. 
Tiger-shell, a beautiful species of vo- 
luta, of a dusky-red colour, spotted all over 
With large irregular blotches of white: it is 
brought from the East Indies, and is about 
two inches and a half in length, and about 
an inch in diameter. 
TILE, in building, a sort of thin brick, 
used on the roofs of houses; of more pro- 
perly a kind of clayey earth, kneaded and 
moulded of a just thickness, dried and burnt 
in a kiln, like a brick, and used in the cover- 
ing and paving of different kinds of military 
and other buildings. The best brick-earth 
only should be made into tiles. 
The tiles for all sorts of uses may now be 
comprised under seven heads, viz. 1. The 
plain tile for covering of houses, which is 
fiat and thin. 2. The plain tile for paving, 
which is also flat, but thicker ; and its size 
9, 10, or 12 inches. 3. The pan-tile, which 
is also used for covering of buildings, and is 
hollow, and crooked, or bent, somewhat in 
the manner of an S. 4. The Dutch glazed 
pan-tile. 5. The English glazed pan-tile. 
6. The gutter-tile, which is made with a kind 
of wings. And 7. The hip or corner-tile. 
"Files, plain, are best when they are firm- 
est, soundest, and strongest. Some are 
duskier, and others ruddier, in colour. The 
dusky- coloured are generally the strongest. 
These tiles are not laid in mortar, but pointed 
only in the inside. 
Tiles, paving, are made of a more sandy 
earth than the common or plain tiles; the 
materials for these last must be absolute clay, 
but for the others a kind of loam is used. 
These are made thicker and larger than the 
common roof-tiles ; and when care has been 
taken in the choice of the earth, and the 
management of the fire, they are very re- 
gular and beautiful. 
Tiles, pan, when of the best kind, are 
made of an earth not much unlike that of the 
paving-tiles, and often of the same; but the 
best sort of all is a pale-coloured loam that is 
less sandy; they have about the same degree 
of fire given them in the baking, and they 
come out nearly of the same colour. These 
tiles are laid in mortar, because the roof 
being very flat, and many of them warped in 
the burning, they will not cover the build- 
ing so well that no water can pass between 
them. 
Tiles, pan, Dutch glazed, get the addition 
of glazing in the fire. Many kinds of earthy 
matter running into a glassy substance in 
great heat, is a great advantage to them ; 
preserving them much longer than the com- 
mon pan-tiles, so that they are very well 
worth the additional charge that attends the 
using them. 
Tiles, pan, English glazed, are in general 
not so good as the lYttch ones under that 
denomination, but the process is nearly the 
same. 
Tiles, Dutch, for chimneys, are of a kind 
very different from all the rest. They are 
made of a whitish earth, glazed and painted 
with various figures, such as birds, flowers, 
or landscapes, in blue or purple colour, and 
sometimes quite white; they are about 6.5 
inches each way, and three quarters of an 
inch thick. They are seldom used at pre- 
sent. 
Tiles, gutter , are made of the same earth 
as the common pan-tiles, and only differ 
from them in shape ; but it is advisable that 
particular care is taken in tempering and 
working the earth for these, for none are. 
more liable to accidents. The edges of these 
tiles are turned up at the larger ends for 
about four inches. They are seldom used 
where lead is to be had. 
Tiles, hip or corner, are at first made fiat, 
like pan-tiles of a quadrangular figure, whose 
two sides are right lines, and the ends arches 
of circles ; the upper end concave, and the 
lower convex the latter being abogt seven 
times as broad as the other ; they are about 
10.5 inches long; but before they are burnt, 
are bent upon a mould in the form of a ridge 
tile, having a hole at the narrow end, to nail 
them on the hip-corner of the roof. 
Tiles, ridge, are used to cover the ridges 
of houses, and are made in the form of a seini- 
cylindrical surface, about 13 inches in length, 
and of the same thickness as plain tiles ; their 
breadth at the outside measures about sixteen 
inches. 
TILIA, lime, or linden-tree, a genus of 
plants of the class polyaodria, and order mo- 
nogynia, and in the natural system ranging 
under the columnifer*. The calyx is quin- 
quepartite; the corolla pentapetalous; the 
caps, is dry, globose, quinquelocular, quin- 
quevalve, and opening at the base. There 
are four species; the europaia, americana, 
pubescens, and alba. The europaxi, or com- 
mon lime-tree, is generally supposed to be a 
native of Britain ; but we are informed by 
Mr. Coxe, that Mr. Pennant told him (on 
what authority is not mentioned) that it was 
imported into England before the year 1652. 
d'lie wood is light, smooth, and of a spongy 
texture, used lor making lasts and tables for 
shoemakers, Ac. Ropes and bandages are 
made of the bark, and mats and rustic gar- 
ments of the inner rind, in Carniola and some 
other countries. The lime-tree contains a 
gummy juice, which being repeatedly boiled 
and clarilied, produces a substance like sugar. 
TILLAN DSIA, a genus of the hexandria 
monogynia class of plants, with a tubulated 
monopetalous llower, trifid at the limb ; the 
fruit is a long, obtusely trigonal, and acumi- 
nated capsule, formed of three valves, and 
containing only one cell, with numerous seeds 
affixed to a long capillary plume. There are 
16 species. 
TILLER of a ship, a strong piece of 
wood fastened in the head of the rudder, and 
in small ships and boats called the helm. 
In ships of war, and other large vessels, 
