A treatise on the human skeleton (including the joints) / by George Murray Humphry.

  • George Murray Humphry
Date:
1858
Catalogue details

Licence: Public Domain Mark

Credit: A treatise on the human skeleton (including the joints) / by George Murray Humphry. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    in walking, is limited by tlie length of tlie stride and the celerity with which the several stages of the step can be conducted. If greater rapidity be required, Running is substituted feet off the for Walking. The difference is that the trunk, instead of ground at the ][3gij^g quietly delivered over from one lecf to the other which same time. & u j o is already upon the ground to receive it, is thrown forward, with a spring, by the muscles of the leg which is leaving the ground, and remains, for a time, suspended in the air, or, rather flying through the air. Hence, in running, both feet are in the air at the beginning and end of each step, that is, in the periods corresponding to those in which both are upon the ground in walking; and the length of the step is no longer limited by the length of the stride, which can be taken while both feet are upon the ground, but superadded to that is the distance to which the body can be driven through the air while both feet are off the ground. It need scarcely be remarked that this propulsion is attended with great effort, and that running is, therefore, considerably more fatiguing than walking. In running, the pei-iod during which each foot is upon Period in which the foot is on the ground (fig. 9, R) is shorter than that in which it is in egioun . ^-j^^ ^.^^ ^^^ ^^^ disproportion increases with the quickness of the step. Indeed, in fast running the foot is on the ground only during the short time in which the trunk is passing vertically over it, and during the first part of the time in which the trunk is being ad- vanced in front of it. The limb is at first bent at the knee and hip, and becomes quickly straightened; the changes which take place correspond- ing with those in the second and third stages of the same period in walking. Thoiigh the first stage can scarcely be said to exist in running; for, as just mentioned, by the time the foot has reached the ground the trunk is already vertically over it, or nearly so; whilst the heel scarcely touches the ground, and the foot revolves, almost exclusively, upon the balls of the toes. The impulse which is communicated by the sudden and forcible lengthening of the limb is sufficient to drive the whole body through the air for a certain distance, and to urge it onwards during the chief part of the period in which the other leg is upon the ground. When the limb has completed its extension and has Period in which the foot is off given to the body the impulse resulting therefrom, it is legroiin . raised from the ground (fig. 8, L), partly, in consequence of its being carried on by the forward movement of the trunk, and, partly, in consequence of the flexion of the hip and knee, which results from