There is a definite daily cycle of variations, amounting to one or two degrees. According to Quain, the temperature of a healthy adult reaches its highest point between 5 and 8 P. M., and is at its lowest from 2 to 6 A. M. A deviation of more than one degree from the normal standard, that is, above 994°, or below 971°, may be regarded as indicative of disease. There is only a range of about twenty degrees within which life can be sustained. A temperature above 108°, or below 93°, will prove almost invariably fatal. The danger is in proportion to the distance from the normal, and to the length of time that the condition continues. Temperature below the normal standard, is far more dangerous than the same number of degrees above, as the following table shows:

Algid collapse... below 95°-again extremely dangerous.

Most, though not all, morbid states, are accompanied by alterations in temperature, some of which are so typical as to be of great diagnostic value. Rise of temperature above 994°, constitutes fever, or pyrexia. It is occasioned either by imperfect loss of heat, or by over production. The amount of heat produced, is proportional to the activity of respiration, and the amount of oxygen consumed. The pulse is generally accelerated in proportion to the elevation of temperature, though the proportion varies in different diseases. In scarlet fever, for instance, the pulse will be quicker than in

typhoid with the same temperature. If the pulse is more rapid than the temperature will explain, it indicates cardiac weakness.

A change of temperature may be the first symptom of disorder, occurring even before indisposition is felt. It is of importance to get this first variation from the normal temperature; and as medical advice is not likely to be called for until more evident symptoms have manifested themselves, every mother as well as every nurse ought to own a clinical thermometer, and to know how to use and read it. She can do no harm, and she may do a great deal of good, by using it upon the first suspicion of a departure from health. A slight variation from the normal is of less serious import in a child than in an adult, unless it is found to be increasing. An increase, beginning each day a little earlier, is a bad indication; a decrease from a high temperature, beginning each day earlier, is a sign of improvement. The daily fluctuations take place also in disease, and are sometimes much exaggerated. Sometimes fever is continuously high, with only the normal amount of variation; or it may be remittent, that is, with a wide range between its highest and lowest points, though never sinking to normal; or intermittent, in which type the temperature alternately rises to febrile height, and falls to or below the normal. In some disorders, as pneumonia, and others similarly initiated with a chill, the rise will be rapid and sudden; in others, there will be at first but slight elevation, which gradually increases. Typhoid is of the latter class, the temperature rising about two degrees daily, but falling again each morning, so that the maximum mark is only reached on the fifth or sixth day. A febrile temperature may be expected to rise toward evening, but in rare cases the ordinary rule will

be reversed, and there will be rise in the morning and remission in the evening. In some cases of typhoid and phthisis, two exacerbations have been observed in the twenty-four hours, with two distinct remissions. Such deviations can only be recognized by testing the temperature frequently. It will be evident that isolated observations have not the value of a regular series. The temperature should be taken at the same hour each day, to exhibit accurately the cycle of fluctuations. An irregularity in temperature, in the course of a disease which has usually a regular type, is indicative of some complication. Or it may depend upon local causes, and be removed with them. Thus constipation will often send up the temperature, which will fall again after its relief. Bad air may have the same effect. The decline of fever, or defervescence, may, like the rise, be gradual from day to day, or sudden, dropping to a steady normal in from six to thirty-six hours.

Temperature may be artificially reduced by applications of cold, or by antipyretic medicines; it may be brought up by external heat and stimulants. The former act most effectively at the times when the temperature has a natural tendency to fall, and the latter. when the tendency is to rise, as the effort of nature is then assisted rather than opposed.

Any great modification of temperature is usually recognizable to the touch, but to measure its extent with mathematical certainty, the clinical thermometer is used. This now familiar little instrument is indispensable to every nurse. Before use the index must be thrown down to a point two or three degrees below the normal. Hold it with the bulb down, and shake until the mercury falls.

The temperature may be taken under the tongue,

in the axilla, or groin, rectum, or vagina. The temperature of the interior of the body is more even, and somewhat more elevated, than that of the surface, so that, when it is taken in either of the natural cavities, the index will reach a point at least half a degree higher than in an artificial cavity. The mouth will be a little cooler than the cavities constantly closed, and the axillæ cooler still, and it will take longer time for the mercury to rise in these places, unless the precaution has been taken to keep the mouth or axilla previously closed for ten minutes, that they may have assumed a steady temperature. A little time may be saved by slightly warming the bulb in the hand before its introduction. Keep the patient well covered for some little time before taking an axillary temperature. The part should not have been exposed for washing or dressing for at least half an hour previously. The axilla must be first dried from perspiration, care be taken that the clothing is not in the way, and the thermometer held firmly in position. This is best done by pressing the arm closely to the side, and flexing it till the hand touches the opposite shoulder. Where great accuracy is needed, the thermometer should be left in place until the index has remained stationary for five minutes. In a very emaciated subject it may be impossible to get a correct axillary temperature.

The temperature is frequently taken in the mouth, the bulb of the thermometer being placed under the tongue. This is not always safe, as there is danger that a child, or an irresponsible patient, may bite off the bulb. The lips must be kept closed during the process.

The rectum gives, perhaps, the most reliable temperature, as there are fewer possible sources of error. This method is always employed for infants. The tube

should be oiled and inserted for nearly two inches. Remember that, if the rectum contains fæcal matter, the index will not reach so high a point as if the bulb comes directly in contact with the mucous membrane.

The length of time required to take a temperature depends not only upon the locality selected, but also to some extent upon the thermometer used. Some will do the work in three minutes, while others take five or ten, other things being equal. Every thermometer in use ought to be annually compared with some standard, as, after a time, it will cease to register correctly. The bulb gradually contracts a little, and too high indications result. Never leave a thermometer with a patient unwatched, unless you are very sure he is to be trusted to take care of it.

Inflammation sometimes gives a local rise of temperature, without affecting the general heat of the body. To test this, a surface thermometer is used, one with the reservoir flattened, so as to receive impressions from the open surface. The scale is the same as that of the ordinary fever thermometer, divided into degrees and fifths, but it is not self-registering. They usually come in pairs matched to work together; but this arrangement has only the advantage of saving time. One will answer every practical purpose. It is to be applied alternately over the seat of inflammation, and over some corresponding part known to be isothermal with it in health. The difference shows the amount of increase in the local heat. This, like the general temperature, will be found to fluctuate, exhibiting periods of exacerbation and defervescence.

Temperatures need not only to be accurately taken, but correctly recorded. Note degree and hour immediately upon taking, without leaving time to forget.