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 by his duties as lecturer in the university. His apparatus resembled closely Galileo's, being a glass globe attached to a long narrow tube partially filled with water, which stood in a small open vessel of water; when the air in the globe is warmed the water in the tube sinks, and on cooling it rises. Sanctorius says the instrument "was used by Hero for other purposes, but I have applied it to the determination of the warm and cold temperature of the air and of all parts of the body, as well as for testing the heat of persons in a fever."

Sanctorius had the thermometer made in a variety of forms for taking the temperature of different parts of the body; in one style the bulb was inserted in the mouth of the patient and the long S-shaped tube was divided into degrees; when so applied the bulb was allowed to be in place during "ten pulse-beats." Sanctorius was the first physician to recognize that the human body has a normal temperature, and to determine variations from it as an aid to diagnosis. He also attempted to ascertain the heat of the moon, but misinterpreted his results; we now know that his instruments were not sensitive enough for the purpose. He made an experiment to measure the relation between