Page:Popular Science Monthly Volume 15.djvu/341

Rh men and animals. We slip into our boots a bellows-sole, which is connected by a tube with a portable odograph. Each pace impresses on the style a small movement, as does each turn of the wheel of a carriage; and, if the paces be absolutely equal, we may measure with certainty the distances traveled. In walking on level ground we take steps of astonishing regularity; but, if the ground rises, the step gains in length; in descents, on the contrary, the steps are shortened. There may result from this slight errors in the distances traversed. Notwithstanding this, the employment of this apparatus will effect a great progress; it may be substituted with many advantages for the pedometer, which gives at the end of a certain time only the paces accomplished, without taking count of the stoppages or the changes of rate.

In short, when we make an experiment on a measured road, if there are produced variations in the length of the tracing represented by a kilometre, we conclude therefrom variations in the length of the pace. Such variations are observed under the influence of the slope of the country, the nature of the soil, the boots we wear, the rate of walking, or the weight carried. These studies in applied physiology have, I believe, a great practical importance, and numerous applications to the march of troops in a campaign.—Nature.



AVING no more documents until 1830, I propose to make a short critical review of Mill's writings and doings in the interval, upon the basis of the information supplied by himself. I will first endeavor, for the sake of clearness, to extract the chronological sequence of the years from 1820 to 1830, which, from his plan of writing, is not very easy to get hold of.

1821. Returns from France (July). Beginning of psychological studies. Condillac.

1822. Reads the History of the French Revolution; inflamed with the subject. Studies law with Austin. Dumont's Bentham excites him to a pitch of enthusiasm. Locke, Helvetius, Hartley, Berkeley, Hume, Reid, Dugald Stewart, Brown on Cause and Effect, Bentham's Analysis of Natural Religion. Began intimacy with Grote. Charles Austin. First published writings in the "Traveller" newspaper.

1823. Utilitarian Society at Bentham's house: Tooke, Ellis, and Graham. Appointment to India House (May 21st). Letters to the 