41 8 On iy Power nf Mm *s firff Movers. 



value wlach rcprcfents the tranfport of the weight of the body of the man. This fot:il 

 etfeft is the greateft pofTible when the man afccnds witlioiit a burthen ; but the ufffut 

 «^^^ is then nothing; It is alfo nothing if the man be loadel fo much as to be fcarcefy 

 capable of moving: and, confequently, there exifts between thefc two limits a value of 

 the load, fuch, that the ufeftil effeft is the greateft pofTib'e. Citizen Coulomb fuppofes 

 that the lofs-of quantity of aftion is proportional to the load (which hypotheils is con-' 

 firmed by experience) whence he obtains an equcition, which treated according to the 

 rules of maxima and iriinima, gives 53 kilograms (ii/lb, avoirdupois) for the weight 

 with which the man ought to be loaded, in order to produce, during one day, by af- 

 cending flairs (un efcalier) the greateft^ ufeful effeft ; and the quantity of aftion which 

 refults from this determination, which has for its value 56 kilograms, raifed through 

 one kilometer, does not fenfibly diifer from the refults of expe'rience'. But this method 

 of working is attended with a lofs of three fourths of the total aftion of men, and 

 confequently cofts four times as much as work, in which, after having mounted a fet' 

 of ileps without any burthen, the man (hould fuffer himfelf to fall by any means, fo as 

 to raife a weight nearly equal to that of his own body. 



The author afterwards examines the work of men walking on an horizontal path, 

 with or without a load. This method is here fimilar to the preceding, and affords (imikir 

 refults. The greateft quantity of a6Kon takes place when the men walk without beiitg 

 loaded ; and is to that of men walking, under a load of 58 kilograms, nearlv as 7 to 4. 

 The weight which a man ought to carr)% in order to produce the greateft ujiftd effefl, 

 namely, that effeft in which th.e quantity of aftion relative to the carrying hfs own 

 weight is dedufted from the total effeft is ^0,4 kilogrammes (or 112 pounds, avoirdu- 

 pois.) 



There is a particular cafe which ahvays obtains with refpeft to burthens cariied in 

 towns ; namely, that in which the men, after having carried their load, return unloaded 

 for a new burthen. The weight they fhould carry in this cafe, to produce the greateft 

 effeft, is 61,25 kilograms, or nearly 135 pounds avoirdupois. The quantity of ufe- 

 ful aftion in this cafe, compared with that of a man who walks freely and without a 

 a load, is nearly as 1 to 5, that is to fay, he employs to pure lofs f of his power. 



The author afterwards fuccefTively treats of the cafes in which men convey burthens 

 on a wheel-barrow, or raife a weight for driving piles, or turn a handle. Under 

 each article he gives the abfolute and comparative refults, comparing each kind of 

 labour to the other methods of employing the forces of man. He finds that by cauCng 

 him to mount a fet of fteps freely and without burthen, his quantity of aftion is at 

 leaft double what he affords in all thefe otfier methods of employing his flrength. The 

 limits of this abftra6l will not permit us to follow him to a greater extent, for which 

 reafon w» fhall confine ourfelves, in order to give a notion of his method to what we 



have 



