THO 
land resumed it, by creating eiglit knxglite : 
however, the revolution unsettled it again, 
and it lay neglected till queen Anne, in 
1703, restored it to the primitive design, 
of twelve knights of St. Andreiy. Kmg 
George I. in the first of his reign, confirmed 
the statutes signed by queen Anne, with 
the addition of several more, among winch 
was that of adding rays Of glory to surround 
the figure of St. Andrew, which hangs at 
the collar: and though from the reforma- 
tion to George I. both elections and in- 
stalments had been dispensed with, his 
maiestv ordered that chapters of election 
should' for the future, be held m the royal 
presence; to which end he ordered the 
o-reat wardrobe to provide the knights bre- 
thren, and officers, with such mantles as the 
statutes of the said order appointed. 
THLASPI, in botany, hastard-cress, a 
genus of the Tetradynamia Siliculosa class 
and order. Natural order of Siliquosm or 
Crnciformes. Cruciferse, Jussieu. Essen- 
tial character: silicle emarginate, obcor- 
date many-seeded ; valves boat-shaped, 
marffined and keeled. There are fourteen 
species. ' ^ 
THOA, in botan'y, a genus of the Mo- 
noecia Polyandria class and order. N atiiral 
order of Urticm, Jussieu. Essential cha- 
racter: calyx and corolla none ; male, sta- 
mens numerous, at the joints of the spike ; 
female, germs two, at the base of the male 
spike, one on each side, sessile; stigma three 
or four cleft ; seed in a brittle shell, covered 
with a bristly web. There is only one spe- 
cies, viz. T. urens. 
THOLES, in marine affairs, small pins 
driven perpendicularly into the gunwale 
of a boat, and serving to retain the oars in 
that space which is called the row-lock ; 
sometimes there is only one pin to each 
oar, as in boats navigated in the Mediter- 
ranean Sea : in that case the oar is retained 
upon the pin, by means of a strop, or of a 
cleat, with a hole through it, nailed on the 
side of the oar. 
THOUINIA, in botany, so named in 
honour of Moiis. Andi'6 Thouin, fellow ot 
the National Institute, and professor of Hor- 
ticulture in the French Museum, a genus 
of the Pentandria Monogynia class and 
order. Natural order of Convolvuli, Jus- 
sieu. Essential character : corolla one-pe- 
talled, bell-shaped, inferior, hispid on the 
outside-; style simple ; drupe. There is but 
one species, viz. T. spectabilis, a native of 
Madagascar, where it was found by Goin- 
merson. 
THO 
THONSCHIEFER, in mineralogy, slate, 
is divided into three sub-species: 1. The 
common argillaceous schistus, which is com- 
posed of silex, alumina, oxide of iron, and 
proportions of carbonated lime and magne- 
sia : it is used for covering houses, and the 
strait-foliated bluish-grey varieties are em- 
ployed as writing slates : tlie setter and 
more compact varieties are made into 
slate pencils. See Schistus, also Slate. 
2. Hone slate, called by Kirwan novacu- 
lite: its colour, is a greenish-grey, or smoke- 
grey, passing to olive and mountain-green ; 
It occurs iu mass, and has a glimmering 
lustre : its fracture in the great is slaty ; in 
the small, splintery : its fragments are ta- 
bular. It is more or less translucent on the 
edges : it is moderately hard, and not very 
frangible. Specific gravity 2.7. It does 
not effervesce with acids, neither is it fusi- 
ble by the blow pipe without addition. It 
is cut into hones for sharpening the finer 
kinds of steel instruments. It is found in 
Bareith, Seifendorf in Saxony, in Bohemia, 
and the Levant ; hence it is called Turkish 
hone : also iu some parts of North Wales. 
3. Black chalk: its colour is greyish or 
bluish black. It occurs in mass : the frag- 
ments are tabular or .splintery. It stains 
the fingers, and gives a somewhat glossy- 
grey streak. It is meagre, but smooth to 
the touch ; is soft, and very easily frangible, 
Before the blow-pipe, without addition, it 
acquires a thin varnish, but does not melt. 
It has been analysed, and found to con- 
sist of 
.... 64.00 
Alumina 
Carbon 
.... 11.00 
Oxide of iron 
96.50 
Loss — 
, 100.00 
It is employed for drawing, and writing 
oil paper and other materials. The best 
kinds come from Italy : it is found in Spain 
also, and in Isla in the Hebrides. 
THORACIC, or Thoracici, a term 
applied to an order of fishes in the Linnaean 
system : the character of this order of fishes 
is, that they have bony gills, and ventral 
fins directly under the thorax. There are 
the following genera belonging to this 
order : 
Centrogaster Chaetodon 
Cepola Coryphama 
