Page:Evolution of the thermometer.djvu/45

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of alcohol and to divide the scale into ten thousandths, or some aliquot part of the total expansion.

Strange notions of natural phenomena were current in Boyle's day and the "Father of Chemistry " was not above crediting absurdities; he quoted Orthelius who wrote: "The liquor distilled from the ore of magnesia, or of bismuth, will swell considerably in the glass it is kept in at the full moon, and subside at the new."

Contemporary with Boyle, another distinguished British philosopher was occupied with improvements in thermometers. Robert Hooke, afterwards secretary of the Royal Society, published in 1664 his "Micrographia;" in this work he says: "I have brought sealed thermometers to a great certainty and tenderness, for I have made some with stems above four feet long in which the expanding liquor would so far vary as to be very neer the top in the heat of summer and preety neer the bottom at the coldest time of winter." Hooke filled his thermometers with "best rectified spirit of wine highly ting'd with the lovely colour of cochineal." To graduate the stem he placed zero at the point which the liquid stood when