BUI 



BUL 



site each other, and the intervals are shut 

 with boards let in between the grooves. 

 This kind of fence against the water is 

 called a batterdeaux, or coffer-dam. The 

 batterdeaux, or coffer-dam, requires a 

 good foundation of solid earth or clay. If 

 the bed of the river be of a loose consist- 

 ence, the water will ooze through it in 

 too great abundance. The sides of the 

 inclosure must be made very strong, and 

 well braced within, to prevent the am- 

 bient water from forcing its way into the 

 batterdeaux. 



AVhere 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 pro- 

 perly placed over it, and kept in this 

 situation by ropes: begin to build, and as 

 the work advances it will sink gradually, 

 and at the same time keep continually 

 bracing the sides with timber, to prevent 

 the ambient water from crushing it toge- 

 ther, and thereby not only spoiling the 

 work, but drowning til e 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 

 which it is to rest : for this purpose the 

 bottom of the caisson should be made 

 very strong. AVhere the foundation is not 

 firm, recourse must be had to piling, as 

 in other such foundations. 



With regard to the superstructure of a 

 stone bridge, the arch stones sometimes 

 terminate in a curve parallel to the in- 

 trados, and sometimes the joints of the 

 arch stones are continued through the 

 spandrils, observing to break joints side- 

 ways; at other times, the upper ends of 

 the arch stones terminate so as to fit the 

 beds and upright joints of every course 

 of stone. The joints of the arch stones 

 are sometimes joggled with plugs,in order 

 to prevent them from passing each other. 

 The piers are^generally solid pieces of 

 masonry from the foundation till they 

 come to the spring, or above the spring 

 of the arch ; thence arches, or complete 

 cylindrical vaults, are sometimes thrown, 

 in order to lighten the bridge, and brace 

 every two adjacent arches between which 

 they are placed. When the abutments 

 are deep, and extend considerably along 

 the road-way at each end, walls on each 

 side of the road-way should be built, 

 similar to those used in aquatic piers, 

 r strengthened with counter- 

 or vaulted under and across the 

 \ hen there is a heavy pres- 



sure of earth between the side of the 

 abutments, these sides should be both, 

 concave in any vertical, and also in any 

 horizontal sections. 



In stone bridges, when the extrados is 

 a curre, 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 in- 

 tersection of the extrados with this face, 

 as this position of the joints is not only 

 more beautiful, but is also more agree- 

 able to the laws of strength, than those 

 bedding joints which have their intersec- 

 tions in horizontal planes. 



BULB, or BULBOUS root, in the anato- 

 my of plants, expresses a root of around 

 or roundish figure, and usually furnished 

 with fibres at its base. See BOTAWX-. 



BULBOCOD1UM, in botany, a genus 

 of the Hexandria Monogynia class and 

 order. Liliaceous plants. Order Spatha- 

 ceae : Narcissi, Jussieu. Essential charac- 

 ter: corolla funnel-form, hexapetalous, 

 with a narrow claw bearing the stamens; 

 capsule superior. There is but one spe- 

 cies, viz. B. vernum, spring flowering bul- 

 bocodium, resembles the common col- 

 chicum in shape, though much smaller ; 

 it is covered with a dark brown skin. 

 About the middle of February, according 

 to the season, the 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 within them very 

 white, before they open far ; though 

 sometimes purplish at first appearing. 

 There is frequently but one flower, and 

 never more than two ; they are smaller 

 than those of colchicum. After the flow- 

 ers are past, the leaves grow to the length 

 of a finger, and in the middle of them 

 rises up the seed vessel, which is smaller, 

 shorter, and harder than that of colchi- 

 cum, and contains many small brown, 

 seeds. It is a native of Spain and of Rus- 

 sia, in mountainous situations. 



BULIMY, a disease in which the patient 

 is affected with insatiable and perpe- 

 tual desire of eating ; and unless he is 

 indulged, he often falls into fainting fits. 

 It is also called fames canina, canine ap- 

 petite. 



In the third volume of the " Memoirs 

 of the Medical Society of London" is in- 

 serted the history of a case of bulimy, ac- 

 companied with vomiting, wherein 379lbs. 

 of meat and drink were swallowed in the 

 space of six days ; yet the patient lost 

 flesh rapidly. A cure was effected by 

 giving- food boiled down to a jelly, fre- 

 quently, and in small quantities. In this 



