WEIGHING-MACHINE. 



jf Heel, and fharp-pointed, in order to reft in a cup or If the load does not exceed the allowed weight, a cer. 

 ocket, r, of fteel, formed in the lower part of a loop or tain toll is charged for the carriage ; bot for all e:{cefs of 

 ink I. The upper end of the loop is fufpended upon a weight, a very heavy toil is charged on each hundred- 

 harp-edged pin fixed in the lever C D, Jig. I, which lever weight as a penalty, the amount of which is incr»afed in 

 s marked X and H in^f^. 5. The link belonging to the proportion to the quantity of over-'veight. (SeeTuRNPiKE, ) 

 ever A A is fufpended on one end of this pin, and the It is a valuable prize for a gate-keeper to fiid a carriage 

 ither loop upon the other end of the fame pin. The lever overloaded. 



" G is made juft the fame as a common lleel-yard. W ElGHina-Machinej for /mall Weights. Thefe are of 



The fpiral, Jig. 6, muft be made very correftly in brafs, different conftruftions, according to the ufe for which they 



nd the line which winds upon it fhould be very flexible, are intended. 



nd of equal thicknefs. After every care has been taken In fome the weight of any body is determined by put- 



3 make all parts of the machine very accurately, they muft ting loofe weights into an oppofite fcale, and thefe weights 



e put together ; and known weights being laid upon the may be either equal weights to thofe which they are to 



latform, the divjfions on the dial ftiould be laid down from denote, as in the cafe of a balance with equal arms, or 



le pofitions of the index. If the dial is thus divided by the weights may be fmaller and applied to the longer arm 



ftual experiment, the machine will weigh very accurately ; of an unequal balance, as iu the fteel-yard. The former is 



by far the moft accurate, and from the facility of proving 



ut its fenfibility will depend upon the (liarpnefs of the cen- 

 ■es of the levers, and the hardnefs of the fteel. When it 



in good order, the addition of a quarter of a hundred 

 eight to three or four tons, on the weigh-bridge, ought 

 > produce a motion of the index. In an average ftate 

 : the machine, it may be depended upon to within half 

 hundred weiglit. 



Mr. Salmon had a patent for this machine in 1796, but 

 s invention is confined to the balance-wheel and fpiral, as 

 ewn in Jigs. 6. and 7. Thefe parts, feparated from the 

 ■eat machine, make a very accurate and complete weighing 

 achine by themfelves, when inclofed in a box ; a common 

 ale, to contain the goods which are to be weighed, being 

 fpended from the lower ^end of the ftrap which winds 

 lund the roller. 



The introdudtion of thefe index weighing-machines for 

 rnpike-roads is of great utility, to diminifh thofe inceffant 

 fputcs between the gate-keeper and the carriers refpett- 

 g the weight of their loads. In the common weighing- 

 achines, the weights, being loofe and of an arbitrary weigiit, 

 jy be changed or diminiihed by the gate-keefler to make 

 e loads appear greater ; and the carrier has no means of 

 tedling this fraud, except by unloading and weighing his 

 rgo in fmall quantities, which is fcarcely prafticable ; 

 ither can he be affured of the manner of weighing, even 



the weights are juft. Another fource of uncertauity is, 

 lether the machine be in exaft balance when there is no 

 id on the platform ; for as the wood imbibes wet and he- 

 mes dirty, it makes confiderable variations in the balance 



the machine. To put the machine in cquililjrio, a heavy 

 :ight is hung on the end of the lever C i^i^fig. 3, and can 



placed nearer to or farther from the centre. This fhould 

 vays be adjuiled, but is frequently negledted, and is difR- 

 It of detection. 



With the index-machine all thefe difficulties are avoided : 

 is conrtrufted by a maker whofe charadler is at ftake, 

 i when once truly made will continue in the fame ftate, 

 • the whole is locked up, fo that the gate-keeper cannot 

 ve accefs to the index. The only defect arifing from age 

 i wear is, that the index becomes lefs fenfiblc, and moves 

 ggifhly and by flarts. This the carrier can try at any time 



preftlng his foot upon the platform ; and he can always 

 ' if the index returns to zero when the load is removed ; 

 d if it does not, he can fee how much the machine is out 



balance. 



The law refpetting weighing carriages is an inducement 



fraud in the gate-keepers ; a certain weight is allowed 



adl of parliament to be carried by each defcription of 

 'riage, which weight is regulated according to the width 



the carriage-wheels, the number of horfcs, and the fea- 

 1 of the year, whether winter or fununer. 



ac 

 its accuracy by placing the weights in either of the fcales^ 

 it has become the legal mode of weighing. Steel-yards are 

 accurate if carefully ufed, but afford many opportunities of 

 fraud in the hands of difhoneft perfons. 



Mr. Medhurft's patent weighing-machine is very ufeful 

 in (hops and warehoufes, being more convenient than the 

 common balance and fcales, and having the fame property 

 of equal arms to the lever. The fcale-boards, inilead of 

 being fufpended from the arms of the balance, are fe- 

 curtly poifed between the arms of a double balance-beam, 

 and are placed at fuch a height as is moil coiivenient to re- 

 ceive the goods which are to be weighed. The weights are to 

 be put into the oppofite fcale, but can be put in either; and 

 the load on the oppofite one, if there is any doubt of the 

 accuracy of the balance. 



When more confiderable weights are to be weighed, equal 

 w-eights are fo inconvenient, tbat fmall machines, fuch as are 

 ufed for carriages, are to be preferred for convenience, as 

 they require only fmall weights in the fcale. 



There is another kind of weighing-machines which requires 

 no loofe weights, but fhews the weight by a pointer or index 

 upon a divided arch, or on a dial-plate. 



The index and balance-wheel of Mr. Salmon's machine, 

 when detached, make a very complete weighing inftrumeat 

 of this kind, as before defcribed. 



Other index machines aft with a pendulum : thus, the 

 fcale to receive the goods is fufpended from a lever, to which 

 a pendulous arm is attached with a heavy weight at the ex- 

 tretnitv to form a pendulum. The application of any weight 

 in the fcale tends to remove the pendulum from its vertical 

 pofition ; and it is a property of a pendidum to increafe in its 

 effort to return to the perpendicular, in proportion to the 

 diftance which it is removed from it. The quantity of de- 

 viation from the perpendicular is indicated by an index or 

 pointer to the divifions on an arch, and thefe divifions are 

 numbered to denote the weight. The machine ufed for 

 weighing hanks of cotton is of this kind, and apothecaries 

 fometim.'S ufe a fimilar inllrument. 



Many of the index machines are made with fprings, which 

 are bent by the application of the weight ; and the degree 

 of their flexure, as determined by fome indexes, is an indica- 

 tion of the weight applied. Several machines of this kind 

 are defcribed in our article Dynanometer ; and although 

 they are rather differently conllructed, to fit them tor mea- 

 furing the ftrength of horfes, &:c. all of them may be con- 

 verted to weighing-machines, by applying a proper fufpend- 

 ing hook, with a fcale to receive the matter to be weighed. 

 A curious machine of this kind was made many years 

 ago by M. Hanin of Paris, and prefentcd to the Society 

 of Arts. The weight is determined by the degree to which 



a femi- 



