W E I 



■ WEIGHING, the aft of examining a body in the ba- 

 " lance, to find its weight. 



The diftillers in London weigh their veffels when full ; 

 and for a half hogfhead, which is thirty-one gallons and a 

 half, allow two hundred one quarter and eleven pounds for 

 the cade and liquor. For a puncheon, they allow fix hun- 

 dred one quarter and two pounds ; for a Canary pipe, eight 

 I hundred a half and feventecn pounds. 



; WEiGHiNG-Cfl^f, in yigriculture, a fort of machine or 

 j contrivance which is made in fomewhat the form or manner 

 ' of an open box or cage, by means of which any fmall ani- 

 1 mal, fuch as a pig, fiieep, calf, or any other of a fimilar 

 kind, may be yery eafily and expeditioufly weiglied, and 

 with fufficient accuracy and correftnefs for the purpofes of 

 the farmer, ftore-maller, and grazier. It is conftrufted on 

 the principle of the common fteel-yard. It has a Ilrong 

 wooden frame, on which there are fteel centres, in which 

 the pivots of the lever are hung. Upon the (hort fide of 

 the lever is fufpended a fort of coop, furrounded by Ilrong 

 oet-work, in which the animal intended to be weighed is 

 put and fecured ; the point of fufpenfion is connefted with 

 the coop by means of two curved iron-rods, which at the fame 

 time form the head of it. A common fcale, in which the 

 weights are to be put, is hung on the longer fide of the lever. 

 See Steel- r^zr^. 



WEiGHiNG-C^a/r, a machine contrived by Sandlorius, 

 to determine the quantity of matter carried off from the 

 body, and that of food taken at a meal ; and to warn the 

 feeder when he had eat his quantum. 



That ingenious autlior, having obferved, with many others, 

 that a great part of our diforders arifes from the excefs in 

 the quantity of our foods, more than in the quality thereof ; 

 as alfo how much a fixed portion, once well adjulled, vifould, 

 if kept to regularly, contribute to health ; bethought him- 

 felf of an expedient to that purpofe. The refult was the 

 weighing-chair : which was a chair fixed at one arm of a 

 fort of balance, wherein a perfon being feated at meat, as 

 foon as he had ate his allowance, the increafe of weight made 

 his feat preponderate : fo that, defcending to the ground, he 

 left his table, viftuals, and all, out of reach. 



WEiGHiNG-i/oi{/J, a building furnirtied with a dock, and 

 conveniences for gauging or afcertaining the tonnage of 

 boats that are to be ufed on a canal. 



WEiGHltSG-Machine for Turnpike Roads, in Mechanics, a 

 machine for weighing heavy bodies, and particularly wheel- 

 carriages. This is commonly done in order to afcertain if 

 a carriage is within the weight allowed by law to be car- 

 ried by fuch carriage on the tunipike-roads ; a weighing- 

 machine, or weigh-bridge, being fixed at every turnpike- 

 gate. See Turnpike. 



Formerly immenfe machines were ufed for this purpofe : 

 the machine was erefted in an open building, beneath which 

 the road pafied, fo that a cart, waggon, or other carriage, 

 could be drawn under it ; ilrong chains were then pafi^ed 

 beneath the body of the carriage, to attach it to the extre- 

 mity of an immenfe fteel-yard. The fulcrum of the fteel-yard 

 was fufpended by a lever, or by pulleys and crane-work, 

 from the top of the buildmg ; and when the carriage was 

 properly fecured, the fteel-yard was hoifted up by the crane- 

 work, fo as to fufpend the waggon, and it could then be 

 weighed by applying the fliding-weight of the fteel-yard to 

 different parts of the divided bar. Several curious machines 

 of this kind are defcribed by Leopold, in his Theatrum 

 Staticnm, 1724. 



This method was tedious and dangerous ; but when 

 lurnpike-roads became more common, a very fuperior ma- 

 chine was introduced, and we now find one at almoi every 



WEI 



turnpike-gate. It is called a weigh-bridge, becaufe the 

 carriage is drawn upon a wooden platform or bridge, which 

 is placed over a pit, made in the hne of the road, to contain 

 the machinery. The pit is walled withinfide, and the plat- 

 form is exaftly fitted to the walls of the pit ; but as it 

 does not touch the walls, it is at liberty to move freely up 

 and down. The platform is fupported by levers, placed 

 beneath it, and is exaftly level with the furface of the 

 road, fo that the carriage is eafily drawn on to it. This 

 is done without any difficulty or lofs of time, becaufe the 

 platform is in the dircft line of the road, and the carriage is 

 only required to ftop for a minute whilft its wheels ftand 

 fairly upon the platform, and the horfes ftand upon the folid 

 ground beyond the platform. A few fmall weights put into 

 a fcale, like that of a common balance, determine the weight 

 of the carriage and its load. If the weight of the carriage 

 is previoufiy known, the weight of the load may be found, 

 by dedufling the weight of the carriage from the total. 



This weigh-bridge is placed at the fide of a fmall houfe, 

 which ufually ferves as a lodgement for the gate-keeper, 

 and the fcale is fituated within the houfe. The platform is 

 fupported by two double levers contained in the pit ; the ends 

 of thefe levers are borne up by a long horizontal lever, which 

 pafTes through one of the fide-walls of the pit, and enters 

 into the houfe : from the end of this lever, a fmall iron rod 

 is carried up to one end of a common fcale-beam or balance, 

 from the other end of which the fcale is fufpended. All 

 the levers are of the nature of fteel-yards, that is, the weight 

 or load of the bridge is applied upon the levers which fup- 

 port it, at points very near to their refpeftive fulcrums, or 

 centres of motion ; whilft the ends of thefe levers are fup- 

 ported, at a very confiderable diftance from their fulcrums, 

 by the long lever, and they bear upon this lever at a point 

 very near to its fulcrum ; but the counterbalancing force, 

 that is, the effort of the weights in the fcale, is applied to 

 the extreme end of the long lever, very far diftant from the 

 fulcrum. For this reafon, a fmall weight, as one pound 

 for inftance, placed in the fcale, will bear up a large weight, 

 for inftance, 60 pounds, or one hundred weight placed 

 upon the platform, according as the machine is conftruiSted. 

 This has an advantage, befides the convenience of fmall 

 weights, viz. that the platform with the carriage does not 

 fink down any perceptible quantity during the adlion of 

 weighing ; for when the weight in the fcale is brought 60 

 equilibrium with the load, any motion or fpace which the fmall 

 weight paftes through, when the fcale-beam vibrates, muft 

 be to the fpace which the platform and carriage pafs through 

 at the fame inftant, in the ratio of the load to the weight. 

 Sometimes, inftead of ufing a fcale-board and detached 

 weights, a long fteel-yard is employed, with a weight to^ 

 flide along upon it to different diftances from tlie centre^ 

 until it will counterbalance the load on the platform ; in 

 that cafe, the lever is graduated to ftievv the weight upon 

 the platform. 



Salmon's Patent Weighing Machine. — This is very generally 

 ufed in the vicinity of London ; it points out the weight 

 on a dial. 



Plate II., Engines, contains figures of a weighing ma- 

 chine of the beil kind. Fig. I. is a horizontal plan of the 

 levers contained in the pit, the platform being taken off to 

 expofe them. The under fide of the platform is fttewn at 

 fg. 2, zndjig. 3. is a vertical feftion of the whole machine. 



E E [fg. 3. ) is the platform ; its upper furface is exaftly 

 level with the ground, and the edge of the planking of the 

 platform is fitted into a border or frame which furmounts 

 the fide walls of the pit, leaving a fmall crevice all round its 

 edges, fo that the platform does not touch the fixed frame, 



K k 2 although 



