BUL 
BUI 
joinings, or by piles driven at certain dis- 
tances from one another, and grooved on 
the sides opposite each other, and the in- 
tervals are shut with boards let in between 
the groves. This kind of fence against the 
water is called a batterdeanx, or coffer-dam. 
The batterdeanx, or coffer-dam, requires a 
good foundation of solid earth or clay.. If 
the bed of the river be of a loose consistence, 
the water will ooze thvoiish it in too great 
abundance. The sides of the inclosure must 
•be made very strong, and well braced 
within, to prevent the ambient water from 
forcing its way into the batterdeanx. 
Where the water is deep, but having a 
sound bottom, a strong chest, called a caisson, 
must be formed, so that the sides may easily 
be disengaged from the bottom of the river, 
being bevelled, where the pier is to be built, 
and the caisson properly placed over it, and 
kept in this situation by ropes: begin to 
build, apd as the work advances it will sink 
gradually, and at the same time keep con- 
tinually bracing the sides with timber, to 
prevent the ambient water from crushing it 
together, and thereby not only spoiling tlie 
work, but drowning the workmen. When 
the pier is of such height as to be deeper 
than the water, the sides may be disen- 
gaged, and the bottom of the caisson will 
remain under the pier, as a footing on wliich 
it is to rest : for tliis purpose the bottom of 
the cai,sson should be made very strong. 
Where the foundation is not firm, recourse 
must be had to piling, as in other such foun- 
dations. 
With regard to tlie superstructure of a 
stone bridge, the arch stones sometimes 
terminate in a curve parallel to tlie intrados, 
and sometimes the joints of the arch stones 
are continued through tire spaiidrils, ob- 
serving to break Joint sideways ; at other 
times the upper ends of the arch stoires ter- 
minate so as to fit the beds and upright 
joints of eveiy course of stone. The joints 
of the arch stones are sometimes joggled 
with plugs, in order to prevent them froin 
passing each other. The piers are generally 
solid pieces of masonry from tire foundation 
till they come to the spring, or above the 
spring of the arch; thence arches, or com- 
plete cylindrical vaults, are sometimes 
thrown, in order to lighten tlie bridge, and 
brace every two adjacent arches between 
which they are placed. When the abut- 
ments are deep, and extend considerably 
along the road-way at each end, walls on 
each side of the road-way should be built, 
siimlar to those used in aquatic piers, and 
either strengthened with counterforts, or 
vaulted under and across tlie road-way. 
AThen there is a heavy pressure of eartii 
between the sides of the abutments, these 
sides should be both concave iii any verticle 
and also in any horizontal sections. 
In stone bridges, when the extrados is a 
curve, and when the work is coursed, the 
intersection of the bedding joint of every 
two courses on the face of the masonry 
ought to be parallel to the intersection of 
the extrados with this face; as this position 
of the joints is not only more beautiful, but 
is also more agreeable to the laws of 
strength than those bedding joints which 
have their intersections in horizontal planes. 
BULB, or Bulbous rool, in the anatomy 
of plants, expresses a root of a round or 
roundish figure, and usually furnished with 
fibres at its base. See Botany. 
BULBOCODIUM, in botany, a genus 
of the Hexandria Monogynia class and 
order. Liliaceous plants. Order Spathaceai : 
Narcissi, Jussieu. Essential character : co- 
rolla funnel-form, hexapetalons, with a nar- 
row claw bearing the stamens ; capsule 
superior. Tliere is but one species, viz. B. 
vernum, spring flowering bulbocodium, re- 
sembles the common colchicnm in shape, 
tliough much smaller ; it is covered with a 
dark brown skin. About the middle of 
Febraary, accm-ding to the season, tlie 
flowers spring up inclosed within three 
brownish green leaves, opening themselves 
as soon almost as they are out of the ground, 
and shew their buds for flowers witliin them 
very white, before tliey open far ; though 
sometimes purplish at first appearing. There 
is frequently but one flower, and never more 
than two; they are smaller tlian those of 
colchicnm. After the flowers are past tlie 
leaves grow to the lengtli of a finger, and in 
the middle of them rises up the seed vessel, 
which is smaller, shorter, and harder than 
that of colchicum, and contains many small 
brown seeds. It is a native of Spain and of 
Russia in mountainous situations. 
BULIMY, a disease in which the patient 
is affected with an insatiable and perpetual 
desire of eating ; and, unless he is indulged 
he often falls into fainting fits. It is also 
called /imies canina, canine appetite. 
In the third volume of the “ Memoirs of 
the Medical Society of London,” is inserted 
the history of a case of bulimy, accompanied 
with vomiting, wherein 379lbs. of meat and 
.drink were swallowed in the space of six 
day^ ; yet the patient lost flesh rapidly. A 
erne was effected by giving food boiled 
