BLA 
to be bored with an augre to a proper depth, 
and a charge of gunpowder introduced. 
The screw is to be turned into the hole till 
it nearly touches the powder; a quick 
match is then to be put down the touch- 
hole till it reaches the charge. The quick 
match is eighteen inches long, to afford the 
operator an opportunity of retiring, after 
lighting it, to a place of safety: it is made 
by steeping a roll of twine or linen thread 
in a solution of saltpetre. 
BLATTA, the cock-roach, in natural his- 
tory, a genus of insects of the order He- 
miptera. The generic characters are, head 
inflected ; antennaj setaceous ; wings flat, 
- subcoriaceous ; thorax flatfish, orbicular, 
margined ; feet formed for running ; horn- 
lets two over the tail. The insects of this 
genus, and their larvaa wander about by 
night, and secret themselves by day. They 
are fond of warmth, and haunt houses, de- 
vouring meal, and whatever provisions they 
can get at : they run with great celerity, 
and are destroyed by the fumes of charcoal. 
In hot climates they are a great pest to so- 
ciety, by not only devouring whatever they 
can get at, but some of the species leave a 
very unpleasant smell, which is apt to re- 
main a considerable time on the articles 
which they have passed over. The largest 
of the genus is, as its name imports, the B. 
gigantea, a native of many of the warmer 
parts of Asia, Africa, and South America, of 
which the following account is given by 
Drury in his “Exotic Insects.” “ The 
cock-roach,” says he, “ are a race of pesti- 
ferous beings, equally noisome and mis- 
chievous to natives and strangers, but parti- 
cularly to collectors. These nasty and vo- 
racious insects fly out in the evenings and 
commit monstrous depredations : they 
plunder and erode all kinds of victuals, drest 
and undrest, and damage all sorts of cloth- 
ing, especially those which are touched 
with powder, pomatum, and similar sub- 
stances; every thing made ofleather, books, 
paper, and various other articles, which, if 
they do not destroy, at least they soil,’ as 
they frequently deposit a drop of their ex- 
crement where they settle, and some way 
or other by that means damage what they 
cannot devour. They fly into "the flame of 
candles, and sometimes into the dishes ; are 
very fond of ink and oil, into which they are 
apt to fall and perish. In this case they 
turn most offensively putrid, so that a man 
might as well set over the cadaverous body 
of a large animal, as write with the ink in 
which they have died. They often fly into 
BLA 
persons’ faces or bosoms, and their legs 
being armed with sharp spines, the pricking 
excites a sudden horror not easily described. 
In old houses they swarm by myriads, 
making every part filthy beyond descrip- 
tion wherever they harbour, which in the 
day-time is in dark corners, behind all sorts 
of clothes, in trunks, boxes, and in short 
every place where they can lie concealed. 
In old timber and deal houses, when the fa- 
mily is retired at night to sleep, this insect, 
among other disagreeable properties, has 
the power of making a noise which very 
much resembles a pretty smart knocking 
with the knuckle upon the wainscotting. 
The B. gigantea, in the West Indies, is 
therefore frequently known by the name of 
the drummer. Three or four of these noisy 
creatures will sometimes be impelled to 
answer one another, and cause such a 
drumming noise, that none but those who 
are very good sleepers can rest for them. 
What is most disagreeable, those who have 
not gause curtains are sometimes attacked 
by them in their sleep : the sick and the 
dying have their extremities attacked, and 
the ends of the toes and fingers of the dead 
are frequently stripped, both of the skin and 
flesh. This insect is not at present known 
m Europe, though many of the other species 
of which Gmelin enumerates 47 , have been 
introduced by ships from the warmer re- 
gions, and are become nuisances in our 
houses. It has been supposed that the gi- 
gantea has been seen once at least in our 
own country, concerning which Mouffet 
writes : “ I have heard from people worthy 
of ci edit, that one of the blatta was found 
on the roof of Peterborough church, which 
was six times larger than the common 
blatta, and which not only pierced the 
skin of those who endeavoured to seize it 
but bit so deep as to draw blood very copi- 
ously : it was as large as one’s thumb, and 
being confined in the cavity of the Avail 
after two or three days it made its escape,’ 
unnoticed by any one.” In Asia this 
species is as large as a good sized hen’s 
egg. B. orientalis, or common black cock- 
roach, was found in America, but has Ion« 
been naturalized in Europe : female with 
biere rudiments of wing-cases and wings : 
egg subcylindrical with a crenate ridge, and 
half as large as the abdomen. This is fre- 
quently met with in London and elsewhere 
under the name of black beetle. B . ameri- 
cana is native of America, and has of late 
years appeared in Europe, having been 
bi ought over in raw sugar. B. irrorata is 
