Page:Evolution of the thermometer.djvu/48

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long after. Meteorological observations were made with Hooke's thermometers by John Wallis, professor of mathematics in Oxford University, and he recorded in a certain paper published in the Philosophical Transactions for 1669, (p. 113), that the "liquor" stood at three and one-half inches on December 26, 1669, and at seven inches in "brisk frosts."

Several novel forms of thermometers were constructed about 1660-62 by the accomplished experimenter in physics, Otto de Guericke, Burgomaster of Magdeburg; they all bore impress of his genius, and one of them was, and still remains, unique in many particulars. It was gigantic in size being above twenty feet long, gorgeous with blue paint and gilt stars, and decorated with the image of a winged angel whose outstretched arm pointed to the temperature at every moment. For convenience the immense air-thermoscope was fastened to the wall of a house on the shady side; it was renowned for its power of showing "the coldest and hottest weather throughout an entire year." The instrument consisted of a large copper globe joined to a long tube one inch wide, of the same metal; the tube was bent upon itself