| Show thermometers in lri making thermometers the tha starting points of temperature taken by the universal agreement of scientific men are the freezing and bailing boiling of pure water the boiling temperature of pure water in rough metallic vessels is always the same for the same degree of atmospheric pressure as indicated by the barometer er As the tha preliminary therefore of graduating a lot of thermometers which have hare been properly llred rifled and sealed they areta are taken kea at allro alimo when the barometer sa rometer stands at thirty inches and arid the tho bulbs being then plunged into pure boiling water gaunic allic vessel the point to which the mercury ascends ta is marked oil on each lubean tube as the boiling point they thay are then transferred to melting snow or ice again 1 ao 2 1 point to 0 o which tiie the mercury descends is maried mardel e saihe I 1 freezing point |
