Muscular Work: A Metabolic Study with Special Reference to the Efficiency of the Human Body as a Machine

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Carnegie institution of Washington, 1913 - 176 páginas

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Página 9 - But no circumstances can be imagined in which this method of procuring heat would not be disadvantageous; for more heat might be obtained by using the fodder necessary for the support of a horse, as fuel.
Página 9 - As the machinery used in this experiment could easily be carried round by the force of one horse (though, to render the work lighter, two horses were actually employed in doing it), these computations show further how large a quantity of heat might be produced by proper mechanical contrivance, merely by the strength of a horse, without either fire, light, combustion, or chemical decomposition; and, in a case of necessity, the heat thus produced might be used in cooking victuals.
Página 9 - ... de variation sensible, la conservation de la chaleur animale est due, au moins en grande partie, à la chaleur que produit la combinaison de l'air pur respiré par les animaux avec la base de. l'air fixe que le sang lui fournit.
Página 11 - Whence it appears that one-quarter of the whole amount of vis viva generated by the combustion of food in the animal frame is capable of being applied in producing a useful mechanical effect, — the remaining three-quarters being required in order to keep up the animal heat, etc.
Página 11 - The majority of the physiologists in the last century, and in the beginning of this century, were of opinion that the processes in living bodies were determined by one principal agent which they chose to call the " vital principle." The physical forces in the living body they supposed could be suspended or again set free at any moment, by the influence of the vital principle ; and that by this means this agent could produce changes in the interior of the body, so that the health of the body would...
Página 11 - mentioned by Magnus is developed by the muscles. The muscles, by their motion, can communicate vis viva to external objects, and, by their friction within the body, can develope heat in various quantities according to circumstances, so as to maintain the animal at an uniform temperature. If these theoretic views be correct, they would lead to the interesting conclusion (which is the same as that announced by Matteucci from other considerations) that the animal frame, though destined to...
Página 11 - In the same time (twenty-four hours) he will consume 12 Ibs. of hay and 12 Ibs. of corn. He is, therefore, able to raise 143 Ibs. by the consumption of one grain of the mixed food. From our own experiments on the combustion of a mixture of hay and corn in oxygen gas, we find that each grain of food, consisting of equal parts of undried hay and corn, is able to give 0'682 to a pound of water, a quantity of heat equivalent to the raising of a weight of 557 Ibs. to the height of a foot. Whence it appears...
Página 11 - They do not suppose that there is any other difference between the chemical and the mechanical actions in the living body, and out of it, than can be explained by the more complicated circumstances and conditions under which these actions take place ; and we have seen that the law of the conservation of force legitimizes this supposition.
Página 9 - Ainsi on peut regarder la chaleur qui se dégage dans le changement de l'air pur en air fixe par la respiration comme la cause principale de la conservation de la chaleur animale, et, si d'autres causes concourent à l'entretenir, leur effet est peu considérable. La respiration est donc une combustion, à la vérité fort lente, mais d'ailleurs parfaitement semblable à celle du charbon; elle se fait dans l'intérieur des poumons sans dégager de lumière sensible...

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