BLO 



144 



BLO 



kinds of blinds are furnished with block- 

 s-heels or rollers to enable the labour- 

 ers in the trenches to push them for- 

 ward. The kind of blinds called chan- 

 deliers are constructed on the principle 

 of the single blind, and are used for the 

 same or similar purposes. 4. The co- 

 verings placed over the most exposed 

 parts in ti.-> saps or the fortress, are also 

 called blinds. These are made of beams 

 over which hurdles or fascines are spread, 

 and these receive a sufficiently thick layer 

 of earth as a covering. 



BLISD'-WORM, a small reptile called 

 also slow-worm, and classed among the 

 serpents, though quite harmless. It is 

 covered with scales and has a forked 

 tongue. 



BLINK, from Sax. blican, to shine. The 

 blink of ice is the dazzling whiteness 

 about the horizon occasioned by the 

 reflection of light from the fields of ice 

 at sea. 



BLIN'KERS, expansions of the sides of the 

 bridles of horses, to prevent them from 

 seeing on either side. 



BLISTER-FLIT, the mutca hi'panica, an 

 insect found in Italy and France, and 

 more or less throughout Europe, but par- 

 ticularly common in Spain, and there- 

 fore called the Spanish fly. It is about 

 two-tlrirds of an inch in length, and one- 

 fourth in breadth, of a somewhat oblong 

 shape, and of a greenish gold shining co- 

 lour, with soft elytra. It is much used in 

 blistering. See CANTHABIS. 



BLOCK, Fr. bloc, Germ, block. A piece of 

 wood in which one or more sheaves or 

 pulleys are placed for the purpose of form- 

 ing tackles in various operations in naval 

 tactics and architectural constructions. 

 Blocks are sinu-le : double, treble, or four- 

 fold, according as the number of sheaves 

 is one, two, three, or four. The sheaves 

 are grooved to receive the rope, and have 

 in their centre a brass bitsh to receive the 

 pin on which they revolve. The sides of 

 the block are called cheeks. A running 

 block is attached to the object to be moved, 

 a standimj block is fixed to some perman- 

 ent support. SeePlLLET. 



BLOCK'ADE, the interception by one bel- 

 ligerent of communication with a place 

 occupied by another, from Ital. bloccare, 

 to inclose. ' A declaration of blockade or 

 siege is an act of national sovereignty, 

 which claims as a right the power of 

 declaring war, and the right which na- 

 tions at war have, of destroying or captur- 

 ing each others subjects or goods, imposes 

 on neutral nations the obligation not to 

 interfere with the exercise of this right 

 within the rules and limits prescribed by 

 the law of nations. 



BLOCK'HOUSE, in fortification, a house 

 made of beams, .joiued together cross ways, 

 tad often doubled, with a covering and 



loopholes. It is usually lanre enough to 

 contain from 50 to 100 men ; is sunk several 

 feet beneath the surface ; is fitted up to 

 receive cannon ; sometimes contains two 

 stories, and is commonly rendered bomb 

 and fire-proof. Its use is to afford a 

 feeble garrison an opportunity of holding 

 out against the cannonade of the enemy 

 till relieved. Blockhouses are also made 

 as places of last resort in the interior or 

 intrenchmentsand in the covered passages 

 of fortresses. 



BLOCK'ING, 1 in masonry, a 



BLOCKING-COURSE, I course of stones 

 placed on the top of a cornice crowning 

 the walls. 



BLOCKINGS, in joinery, small pieces of 

 wood fitted and glued to the interior angle 

 of two boards or other pieces, with a view 

 to strengthen the joint. 



BLOCK-TIN, tin cast into blocks or in- 

 gots ; it is generally less pur" than grain- 

 tin. 



BLOM'ART. 8ft BLOOM. 



BLOOD, Germ, bhit, Fr. sang. The red 

 fluid contained in the blood-vessels of 

 animal bodies. It is found in the mam- 

 malia, in birds, in reptiles, and in fishes. 

 In the last two classes of animals, the tem- 

 perature of the blood is much lower than 

 in the former, for which reason they are 

 distinguished by the uiTnc of cold-blooded. 

 while the others are termed warm-blooded 

 animals. Insects and worms, instead of 

 red blood, have a juice of a whitish colour, 

 which is called while-blood. In the mam- 

 malia the blood circulates in the arteries 

 and veins: it is bright red in the former 

 and purple in the latter. It consists : 

 1st, of a colourless transparent solution of 

 several substances in water; and 2nd, of 

 red undissolved particles diffused through 

 'the solution. "\Vhen fresh drawn from 

 the vessels, it rapidly coagulates into a 

 gelatinous ma*s called the evaculum or 

 clot, from which, after some time, a pale 

 yellow fluid oo7.es forth, called the serum. 

 The coagulum may be divided into two 

 parts the cmor, or that part of the blood 

 which is intrinsically red andcoagulable, 

 and the lymph or fibrine to which the 

 coagulation of the blood is to be ascribed. 

 The specific gravity of the blood varies 

 from 1-053 to 1'057 at 60. In law, a kins- 

 man of the whole blood is one who descends 

 from the same couple of ancestors ; of the 

 half-blood, one who descends from either 

 of them singly by a second marriage. 



BLOOD'-HEAT, \ a fluid raised to the tem- 



BLOOD'-HOT, ) perature of the blood 

 (98 Fah.), is blood-hot. 



BLOOD-HOCND, the ctinis sngar, Lin., and 

 chien courant, Buffon. A variety of the 

 common dog, remarkable for the perfec- 

 tion of its sense of smell. Owing to this 

 circumstance, the blood-hound was an- 

 ciently muck employed in pursuing cii- 



