Page:Popular Science Monthly Volume 80.djvu/136

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THE POPULAR SCIENCE MONTHLY

The condition of the roads, whether dusty or muddy, indicates in a general way the occurrence or lack of recent rainfalls. And thus, through a long list, we might go on. Non-instrumental, even irregular and scattering observations of meteorological conditions, and of their effects, are well worth while, if intelligently made. Such observations should be more generally undertaken.

During the short semi-vacation of the past summer I have found much interest in reading the "Journals" of the Lewis and Clark Expedition "to the sources of the Missouri, across the Rocky Mountains, down the Columbia River to the Pacific in 1804–06" What struck me particularly was the remarkably clear picture which I gained of the climatic conditions of the then unknown country through which, amid great hardships and many dangers, this famous expedition passed. The leader of the expedition was charged by the President with reporting upon very many matters besides meteorology.[1] Yet, in spite of the many difficulties of the journey, and with only one instrument — a thermometer — which was unfortunately broken before the end of the trip, the observing eye of Captain Lewis was able to note a variety of meteorological and climatic facts which give a vivid picture and emphasize, in a striking manner, the kind and the value of simple weather observations which any intelligent traveler can take.[2] In view of the many hardships of the journey, it is surprising to see how few gaps there are in the record, which covers the period January 1, 1804—September 30, 1805. Between May 14 and September 18, 1804, there comes the only considerable gap, with the significant comment: "The party were then just beginning the ascent of the Missouri, and it is probable that amongst the many other important things which engrossed their attention this was omitted." The tables give date, and thermometer, weather and wind direction at sunrise and 4 p.m.; also the rise and fall of rivers, in inches and feet.

The thermometer readings have, perhaps, less value than might be expected, partly because they could not be continued throughout the ex-

  1. President Jefferson instructed Captain Lewis to report upon climate as follows: "Climate, as characterized by the thermometer, by the proportion of rainy, cloudy and clear days; by lightning, hail, snow, ice; by the access and recess of frost, by the winds prevailing at different seasons; the dates at which particular plants put forth, or lose their flower or leaf; times of appearance of particular birds, reptiles or insects."
  2. Captain Lewis's scheme of notation of weather was as follows :
    f, fair weather. c, cloudy.
    r, rain. s, snow.
    h, hail. t, thunder.
    l, lightning. a, after, as f a r means fair after rain which has intervened since the last observation.
    c a s, cloudy after snow intervening.
    c a r s, cloudy after rain and snow.