Page:Evolution of the thermometer.djvu/12

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The word "thermoscope" first appears in print in the treatise "Sphæra mundi, seu Cosmographia demonstrativa," written in 1617 by Giuseppe Bianconi and printed at Bologna in 1620.

The word "thermometer" is first found in Leurechon's "Récréation mathématicque," (1624) already mentioned; his description of the instrument is the earliest that gives a clear notion of those in current use at the beginning of the seventeenth century, and is marked by charming simplicity of language.

"It is an instrument of glass which has a little bulb above and a long neck below, or better a very slender tube, and it ends beneath in a vase full of water, or it is curved behind and has another little bulb into which water or any other liquid may be poured... It is used thus: Put into the vase below some liquid colored blue, or red, or yellow, or other color not too dark, like vinegar, wine, or reddened water, or aqua fortis which has been used to etch copper. Having done this, I say in the first place that as the air enclosed in the bulb becomes rarefied or condensed the water will plainly ascend or descend in the tube; this you can easily test by carrying the instru-