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their muscular exertion required to move them-selves along, is observable upon the coachesand other vehicles upon the common roads.
To obtain a sort of approximation to theenergy of the power of horses at different ratesof speed, I formed a kind of rule, on whichI founded my calculations. Taking the forcewhen continually exerted for ten hours, travel-ling at the rate of two miles an hour, or fortwenty miles a day, as deduced from the pre-ceding experiments, to be equal to 112 lbs.I made this a general expression, for his accu-mulated performance.
I found, when a horse travelling with a loadwas left at liberty to assume what pace hepleased, that heavy horses, such as used inExperiments III. and IV. , generally fall into apace of two miles an hour ; and lighter horses,such as in Experiment V., into two miles anda half an hour ; I considered these as the paceswhere the muscular exertion of the horse suf-fered least in performing a certain quantity ofwork, and at which his effect would be thegreatest, as I invariably found, on pushing ahorse at a more rapid rate, he was more dis-tressed in performing the same work. I thentook 112 lbs., which, when the friction is equalto the 200th part of the weight, would be tentons or 200cwt., multiplied by two miles an