Impressions of America

Abstract

THE impressions were obtained during a pleasure trip to Niagara, the Yellowstone Park, San Francisco, the Yosemite, Utah and Colorado Springs. The author refrains from citing any of the scientific work dealing with the remarkable features of those interesting regions, but gives a graphic account of what he himself saw, and outlines a number of interesting hypotheses to account for some of the phenomena. Some of these are interesting because they show how a man of scientific habits of thought may from a hasty glance often reach conclusions very similar to those which the specialists who have studied the subject for years have demonstrated to be correct. We cannot accept Mr. Porter's ingenious hypothesis that the spiral ridges of the trunks of many trees in the Yellowstone Park are due to unequal heating by the sun and the uniform rotation of the earth, because he does not buttress it with the necessary explanation why trees in other places in the same latitude where the sun also shines unequally and the earth rotates uniformly do not also incline to a screwy form. But the little appendix on the Gulf Stream is a neat demonstration from the study of a single bottle-chart of the seasonal variation of the Gulf Stream and its attendant drift. Of course the deduction is not new; the fine charts of North Atlantic currents grouped for two-monthly intervals by the Meteorological Office bring it out perfectly, and the labours of American, British, and Scandinavian ocean-ographers, and of the Prince of Monaco, have done much to find the reasons for the observed variations. We might venture, however, to remind Mr. Porter that the course of the Gulf Stream shown on a single small scale map is as conventional and empirical a representation of oceanic circulation as the isotherms on a map of mean annual temperature are of the climates of the world. The generalisation in no way implies that the seasonal changes are unknown.

Impressions of America.

By T. C. Porter (Oxon.), Fellow of the Chemical Society, of the Royal Astronomical Society, and of the Physical Society of London. Illustrated with diagrams and stereoscopic views. Pp. xviii + 242. (London: C. Arthur Pearson, Ltd., 1899.)