each containing two or three dark brown feeds tafting 
like Garlick. It flowers in June, and the feeds which 
are an ingredient in Theriaca, ripen in Auguft. 
The third fort is an annual plant, which grows natu- 
rally in the northern counties of England. The 
italics of this rife about nine inches high, which are 
divided at the top into feveral branches, which are 
clothed with oblong heart-fhaped leaves, whofe bafe 
embrace the (talks ^ they are fmooth and entire. The 
flowers are final!, white, and are produced in loofe 
ihort fpikes at the end of the branches : they appear 
the beginning of June, and the feeds ripen early in 
Auguft. 
The fourth fort is an annual plant, which grows na- 
turally in feme parts of England ^ the ftalk rifes 
about four inches high, is Angle, and never branches 
out the leaves embrace the (talks at their bafe ; the 
flowers are produced at the top of the (talks •, the 
petals are the fize of the empalement, which are 
fbcceeded by roundifh heart-fhaped pods, containing 
round feeds. 
The fifth fort grov/s naturally in Sicily •, this is a bi- 
ennial plant, whofe (talks rife eight or nine inches 
high, branching out toward the top, and are garnifh- 
ed with blunt thick leaves, of a grayifh colour, which 
are fpear-fhaped and entire ; they are placed oppofite, 
fitting clofe to the ftalk ; they have a bitter warm 
tafte. The flowers are produced in loofe fpikes at 
the top of the (talks •, they are fmall and of a purple 
colour, having four heart-fhaped petals placed in 
form of a crofs ; thefe are fucceeded by heart-fhaped 
cods of a fine green colour, which are divided into 
two cells, each containing three or four fmall, oblong, 
yellowifh feeds, which have an acrid tafte. It flowers 
in June,, and the feeds ripen in Auguft. 
The fixth fort is an annual plant, which grows natu- 
rally in the northern parts of Europe ; this rifes about 
fix or eight inches high. The ftalk branches toward 
the top, and is garni Ihed with oblong, fmooth, blunt 
leaves which are a little indented ; thefe fit clofe to 
the ftalk, and, if bruifed, have a ftrong feent of 
Garlick. The branches are terminated by loofe 
fpikes of fmall white flowers, compofed of four 
roundifli petals, placed in form of a crofs •, thefe ap- 
pear in June, and are fucceeded by fwelling round- 
ifli pods, containing a few dark brown feeds which 
ripen in July. 
The feventh fort grows naturally in Wales, and in a 
few places in England ; this has a perennial creeping 
root. The lower leaves are oblong and hoary *, they 
are very (lightly finuated, but not indented on the 
ed»es. The ftalks are about five or fix inches long, 
and are bent toward the ground ; the flowers are ra- 
ther larger than thofe of the firft fort, but are of the 
fame forms the pods are hoary, but. not hairy. It 
flowers in May, and the feeds ripen in July. This 
grows naturally on the fide of a bank beyond Wandf- 
worth in the road to Putney. 
The eighth fort grows naturally upon the Alps, and 
in fome parts of Yorkfliire in dry ftony paftures. 
The root of this is perennial and creeping ; the ftalks 
rife four or five inches high j the lower leaves are 
wedge-fhaped, being broad and rounded at their 
points, but narrow at their bafe, of a deep green co- 
lour, and entire ; thofe upon the ftalks are rounder, 
and fit very clofe. The flowers are produced in 
loofe fpikes at the end of the branches ; they are fmall 
and white, (haped like thofe of the other forts, and 
appear in May, thefe are fucceeded by roundifli 
heart-fhaped pods divided into two cells, each con- 
taining two or three brown feeds which ripen in July. 
Thefe plants are propagated by feeds, which fhould 
be fown where the plants are to remain, which may 
be performed either in the fpring or autumn, but the 
latter is to be preferred, becaufe the feeds at that fea- 
fon never fail j and the plants which come up before 
winter will grow much ftronger, and produce a great- 
er quantity of feeds than thofe which are fown in the 
fpring, efpecially if the feafon proves dry ; and there 
is very little danger of the plants being injured by 
froft in winter, if they are upon dry ground. When 
the plants come up, they will require no other care 
. but to thin them where they are too clofe, and keep 
them clean from weeds. 
The two forts which are firft mentioned, may be cul- 
tivated for their feeds to be uied in medicine, fo thefe 
may be fown thin upon beds of light ground, in the 
fame way as for other garden plants, and when they 
come up, the ground (hould be hoed to deftroy the 
weeds, and where the plants are too thick, they (hould 
be cut up in the fame manner as is pradifed for Oni- 
ons, Carrots, &c. leaving them three or four inches 
apart, and by twice hoeing the ground, if it is well 
performed, and in dry weather, will keep the ground 
clean till the feeds are ripe. 
The other forts are feldom cultivated but in botanic 
gardens for variety, fo a few plants of each will bd 
iufficient ; therefore thefe may be fown in drills, and 
when the plants come up they muft be thinned, and 
kept clean from weeds. If the feeds of thele plants' 
are permitted to fcatter, the plants will come up 
without care,, 
T.H1 ST L, E. See Carduus. 
THORN APPLE. See Datura. 
T HORN, the Glaftenbury. See Mespilus and Cra- 
TEGUS. 
thunder is defined by fome to be a noife in the 
lowed: region of the air, excited by a fudden kindling 
ot fulphureous exhalations. 
Some alfo account for it, by fuppofing two clouds 
impending over one another, the upper and rarer 
whereof becoming condenied by a frefh acceflion of 
the air, raifed thither by warmth from the lower 
parts of the atmofphere, or driven upon it by the* 
wmd, immediately falls forcibly down upon the lower 
and denier clouds, by which fall the air interpofed 
between the two being compreffed, that next the ex- 
tremities of the two clouds is fqueezed out, and leaves 
room for the extremity of the upper cloud to clofe 
tight upon the under. Thus a great quantity of air 
is inclofed, which, efcaping through fome winding 
irregular vent or paffage, occafions the noife we call 
Thunder. 
But this only reaches to the phenomena of Thunder 
heard without lightening, and in effedt we have now 
a better folution : that Thunder is not occafioned by 
the falling of the clouds, but by the kindling of ful- 
phureous exhalations in the fame manner as the noife 
of aurum fulminans. 
Sir Ilaac Newton fays, there are fulphureous exhala- 
tions always afeending into the air, when the earth is 
dry •, there they ferment with the nitrous acids, and 
fometimes taking fire, generate into Thunder, light- 
ning, &c. 
That befides the vapours raifed from water, &c. 
there are alfo exhalations carried off from fulphur, 
bitumen, volatile falts, &c. is pad all doubt. The 
vaft quantity of fulphureous and bituminous matter 
all over the furface of the earth, and the volatile 
falts of plants and animals, afford fuch an ample dock 
thereof, that it is no wonder the air fhould be filled 
with fuch particles, raifed higher and lower, accord- 
ing to their greater or lefs degree of fubtilty and acti- 
vity, and more copiouOy fpread in this or that quar- 
ter, according to the directions of the winds, &c. 
The atmofphere about the earth abounds with nitrous 
particles of a fpirituous nature, which are every- 
where carried along with it ; befides which fort of 
particles, there are others raifed up into the air which 
may be fomewhat of the nature of fulphureous, ni- 
trous, and other combuftible bodies, as we fee fpirit 
of v/ine, fpirit of turpentine, camphire, and almoft: 
all other combuftible bodies, will by heat be rarefied 
into the form of air or ftnoke, and be raifed up into 
the air. 
All which, if they have a fufficient degree of heat, 
will catch fire, or be turned into flame by the nitrous 
parts of the air, as thoufands of experiments might 
be brought to prove. 
Dr. 
