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80
EVOLUTION OF THE THERMOMETER.
from freezing-point of water to 90° a temperature equal to that of warm water capable of being endured by the hand held still, certainly a very vague standard but perhaps sufficiently accurate for vegetable life.
The proper temperatures for specified plants were as follows, the degrees being those given by Hales.
| Hales' Table. | |
| Melon thistles | 31 |
| Ananas | 29 |
| Piamento | 26 |
| Euphorbium | 24 |
| Cereus | 21 |
| Aloes | 19 |
| Indian figs | 16 |
| Ficoides | 14 |
| Oranges | 12 |
| Mistles | 9 |
| (Phil. Trans., Apr.-June, 1727.) | |
These instruments were used by the eminent botanist, Rev. Stephen Hales, who describes them in his "Vegetable Statics," 1727 (p. 61). Dr. Hales remarks that "64 of these degrees is nearly equal to the heat of the blood of animals," which he determined by placing the "ball of the thermometer in the blood of an expiring ox." The "temperate" point was about 18 of these degrees.
