BLO 
.of a man, and four or five feet asunder, used 
particularly at the heads of trenches, when 
they are extended in front towards the gla- 
cis ; serving to shelter the workmen, and pre- 
vent their being overlooked by the enemy. 
BLINK, of the ice, in sea language, that 
dazzling whiteness about the horizon which 
is occasioned by the reflection of light from 
the fields of ice. 
BLISTER, in medicine, a thin biadder 
containing a watery humour, whether oc- 
casioned by burns and the like accidents, 
or by vesicatories laid on different parts of 
the body for that purpose. 
BLITUM, in botany, a genus of the 
Monandria Digynia class and order. Natu- 
ral order of Holoraceas ; Atripiices, Jussieu. 
Essential character : calyx trifid ; petal 
none ; seed one, with a berried calyx. 
There are four species, of which B. capitation 
is an annual plant with leaves somewhat like 
those of spinach ; the stalk rises about two 
feet and a half high in gardens ; the upper 
part of it has flowers coming out in small 
heads at every joint, and is terminated by 
a small cluster of the same'. After the 
flowers are past, these little heads swell to 
the size of wood strawberries, and when 
ripe have tiie same appearance, bei.,J very 
succulent and full of a purple juice, which 
stains the hands. It is commonly called 
strawberry blite, strawberry spinach, or 
bloody spinach; by some, berry-bearing 
orach. Native of Switzerland, the Grisons, 
Austria, the Tyrol, Spain, and Portugal. 
B. virgatum seldom grows more than 
one foot high, with smaller leaves than the 
capitatum, but of the same shape. The 
flowers are small, and collected into little 
heads, shaped like those of the first, but 
smaller, and not s > deeply coloured. A na- 
tive of the South of France, Spain, Italy, 
and Tartary. Of the other species, the 
one rises more than three feet high : the 
other is a very low plant, and is found in 
Tartary and Sweden. 
BLOCKS, on ship-board, is the usual 
name for what we call pullies at land. They 
are thick pieces of wood, some with three 
four, or five shivers in them, through which 
all the running ropes run. Blocks, "whether 
single or double, are distinguished and call- 
ed by the names of the ropes they carry 
and the uses they serve for. 
Double blocks are used when there is 
occasion for much strength, because they 
will purchase with more ease than single 
blocks, though much slower, 
BLO 
B ock and block, is a phrase signifying 
that two blocks meet, in haling any tackie or 
halliard, having such blocks belonging to 
them. 
The blocks now used in the navy are 
made in Portsmouth by means of circular 
saws and other machinery, which have been 
lately erected by a most ingenious mecha- 
nician. This machinery performs the several 
operations from the rough timber to the 
perfect block, in the completest man- 
ner possible. The whole is worked by 
means of a steam engine; the manual labour 
required is simply to supply the wood as it 
is wanted to the several, parts of the machi- 
nery, so that the commonest labourer almost 
may be made to act in this business with 
very little instruction. 
Fish block is hung in a notch at the end 
ot tire davit; it serves to hale up the fiooks 
of the anchor at the ship’s brow. 
Snatch block is a great block with a 
shiver in it, and a notch cut through one of 
its cheeks for the more ready receiving of 
any rope ; as by this notch the middle part 
of a rope may be reeved into the block 
without passing it endwise. It is commonly 
fastened with a strap about the main-mast, 
close to the upper deck, and is chiefly used 
for the fall of the winding tackle, which is 
leeved into this block, and then brought to 
the capstan. 
Block house, a kind of wooden fort or 
battery, either mounted on rollers or on a 
vessel, and serving either on the water or 
in counterscarps and counter approaches. 
The name is sometimes also given to a brick 
or stone fort built on a bridge, or the brink 
of a river, serving not only for its defence 
but for the command of the river both 
above and below : such was that noted block- 
house anciently on the bridge of Dresden, 
since demolished on enlarging the bridge. 
BLOCKADE, in the art of war,* the 
blocking up a place by posting troops at all 
the avenues leading to it, to keep supplies 
of men and provisions from getting into it ; 
and by these means proposing to starve it 
out without making any regular attacks. 
To raise a blockade is to force the troojts 
that keep the place blocked up front their 
posts. 
BLOOD is a well-known fluid, which 
circulates in the veins and arteries of the 
more perfect animals. It is of a red co- 
lour, has a considerable degree of consis- 
tency, and an unctuous feel, as if it con- 
tained a quantity of soap. Its taste is 
slightly saiine, and it has a peculiar smell. 
