Supposing a Thermometer is put into any one's hands, reading as at Diagram _A_ 104°, how is the Index to be replaced to the position it occupies in Diagram _B_? Hold the Thermometer by its upper end (the bulb being considered the lower end) then swing it round with your arm, suddenly stopping the arm with a jerk, this jerk causes the Index to fall towards the bulb, continue this, and after each jerk see how far the Index has fallen, when it has got well under the arrow →, the Thermometer for an ordinary case is ready for use. When, however, one expects a low temperature, it is best to have the Index of the Thermometer at or under 95°. [Illustration: Fahrenheit's Scale.] How and when to apply the Thermometer. With grown up children and adults I have always found it more convenient to take the Temperature by placing the bulbous end of the Thermometer into the mouth under the tongue, keeping it there, with the mouth, shut, for the requisite time, the patient in the meanwhile breathing only through the nostrils; with infants the most convenient place is to put the Thermometer in the flexure of the thigh, laying one of the thighs somewhat across the other, but being careful not to allow the clothes to touch the Thermometer; some prefer to place it in the armpit, or axilla. This I have not found always as convenient as the other two localities; any of these, however, is good for the purpose. Use the one you may deem most convenient, but be careful to keep the clothes from coming into contact with the Thermometer. Thermometers are now made with such a rapid action, that at the very longest they do not now require to be kept in position for more than three minutes. Immediately after having made an observation note down the temperature, along with the time at which the observation was taken; having done so, and not before, wash the Thermometer, but _not with hot water_, _and then_ jerk down the Index; so that the Thermometer is ready for future use. If the reading is in any way a doubtful one, take another observation at once. If there is any anxiety connected with the case, it is advisable to take an observation every three hours, so long as the patient is awake; _never disturb_ a patient during natural sleep for the purpose. Ordinarily take an observation two or three times during the day, but at set hours and at regular intervals, always noting the time. Whenever the temperature of a patient is found to be below or above the _normal_ 98·4°, viz., the arrow-mark on the Thermometer, then watch the case, as one requiring care. If the temperature has fallen as low as 97°, or gone up to 100°, make up your mind that there is something wrong; be vigilant. But a falling temperature below 97° means danger from collapse, and a rising one reaching 105° is a dangerous fever heat. In the last two occurrences remedial agents require to be applied to at once, and medical assistance urgently asked for.