GRA 



CRA 



CRADLE, among shipwrights, a timber 

 frame made alcngthe outside of a ship by 

 the bilge, for the convenience of launch- 

 ing her with ease and safety. 



CRAFT, in the sea language, signi- 

 fies all manner of nets, lines, hooks, &c. 

 used in fishing. Hence all such little 

 vessels as ketches, hoys, and smacks, 

 &c. used in the fishing trade, are called 

 small craft. 



CRAMBE, in botany, a genus of the 

 Tetradynamia Siliquosa class and order. 

 Natural order of Siliquosse Cruciformes. 

 Essential character : filaments, the four 

 longer two-cleft at the end, one only of 

 the tips bearing an anther : berry dry, 

 globose, deciduous. There are six spe- 

 cies, of which one is C. maritima, sea- 

 colewort ; the roots of this plant creep 

 under ground, whereby it propagates 

 very fast. The whole plant is smooth, 

 glaucous, and sometimes tinged with pur- 

 ple ; several stalks arise, about two feet 

 high, spreading, much branched, bearing 

 sessile leaves. The flewers or long pe- 

 duncles are white. The fruit at first 

 ovate, terminated by the blunt stigma, 

 afterwards nearly spherical, the size of 

 large peas. The young leaves, covered 

 up with sand, and blanched, 'are boiled 

 and eaten as a great delicacy. It is found 

 on the sandy and beachy coasts of Swe- 

 den and Denmark ; it is also common in 

 many parts of England, particularly in 

 the west. 



CRAMP, in medicine, a convulsive 

 contraction of a muscular part of the 

 body, being either natural, as in convul- 

 sive constitutions, or accidental, from liv- 

 ing in cold places, under ground, &c. It 

 affects all parts indifferently, but the ham, 

 calves, feet, and toes, oftener than the 

 arms and hands. 



An effectual preventative for cramp in 

 tfce calves of the legs, which is a most 

 grievous pain, is to stretch out the heel 

 of the leg as far as possible, at the same 

 time drawing up the toes to the body. 

 This will frequently stop the progress 

 of a fit of the cramp after it has commenc- 

 ed ; and a person will, after a few times, 

 be able in general to prevent the fit com- 

 ing on, though its approach be between 

 sleeping and waking. 



CRANE. See Gnus. 



CRANE, in mechanics, a machine for 

 raising goods into loft, or from vessels to 

 wharfs, or for lowering them from 

 heights, &c. in a safe manner, and by the 

 application of a comparatively small 

 power. Numberless contrivances have 

 been resorted to for these purposes ; the 

 first of them appears to have been the 



great drum-wheel, in which one or more 

 men, an ass, &c. being made to walk, a 

 rotary motion followed, whereby a rope 

 fastened to the axis of the wheel was 

 wound up, and with it whatever weight 

 the power thus created was capable of 

 lifting. But it was found that various 

 fatal accidents attended this piece of 

 machinery ; for when the man slipped, 

 the wheel would obtain a reverse mo- 

 tion, and by its accumulated velocity 

 would dash him to pieces. On the other 

 hand, if the rope suspending the weight 

 gave way, the motion of the wheel, it be- 

 ing released from opposition, became so 

 accelerated as to produce the same fatal 

 effects. 



An improvement upon this was the 

 inclined plane, (seen in fig. 1, PI. IV. 

 Miscel.) which having ribs, or battens, 

 all pointing to its centre, is moved by a 

 man walking either nearer to or further 

 from the axis, according to the weight to 

 be raised, his greatest power being near 

 the edge ; the rope x, sustaining the 

 weight o, passing through the pully y, 

 and winding on the axis/>, as it revolves 

 in consequence of the man's pressure. 

 To prevent accidents, the man has hold 

 of the arm n, projecting from the post z ; 

 so that, in case of a slip, he might save 

 himself by bearing thereon. 



But though this plan is certainly a 

 great improvement, yet it cannot be con- 

 sidered as altogether safe, and it takes up 

 so much space, that it is very rarely in 

 use. The windlass, worked by various 

 different powers, and those variously ap- 

 plied, has in general superseded all other 

 practices. It is to be lamented that some 

 are too complex . and expensive, which 

 would otherwise prove highly servicea- 

 ble. We give that in fig. 2, as being 

 cheap and effective. It consists merely 

 of a barrel, e, to which three concentric 

 iron wheels, a, b, c, all graduated with 

 equidistant teeth, and laying in one 

 plane, secured also by cross bars, are 

 affixed. The small wheel D, having 

 teeth fitting to those on either wheel, 

 may be brought forward to work in 

 either a, 6, ore, at pleasure. Now D be- 

 ing one foot in diameter, and a being 1 

 two feet, the latter will revolve once, 

 while the former revolves twice : this 

 power is suited to light weights. When 

 the resistance is greater, the power must 

 be increased by removing D farther from 

 the centre of the windlass e, and apply, 

 ing it to the second wheel b, which be- 

 ing three times the diameter of D, will 

 turn only once while the latter makes 

 three revolutions: again, when the 



