Page:Evolution of the thermometer.djvu/10

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9
GALILEO'S OPEN AIR-THERMOMETER.

"Grondige oplossinge van de natuur en eyggenschappen der elementen, Amsterdam, 1732." The other copy is in German and bears the date 1715. (Poggendorff, the German historian of physics, admits never having seen an edition of this treatise by Drebbel.)

The Dutch version contains a full-page woodcut representing a retort hanging by a chain from a hook in a beam, the mouth of the retort is under water in a basin, and beneath it is a fire; on the surface of the water are seen bubbles of air issuing from the retort; the whole is observed by two men in out-door costume. The text accompanying this picture, when translated, reads as follows: "Heat makes air and water subtle and light; cold, as the opposite of heat, makes them smaller and presses them together and condenses all the air that the heat had made to rise, as may be clearly shown when a glass retort is hung with the mouth in a bucket of water and fire is placed under the belly. We shall then see that as soon as the air in the glass begins to get hot, that air rises out of the mouth of the retort, and the water gets full of bubbles, and this continues so long as the air gets hotter; but if the fire be removed from beneath the retort