In a number of experiments of the same nature as the last, where one hand was plunged in water cooled down by ice, the other hand, which was not subjected to the action of the cold bath, lost nearly 5° It. in temperature.
It is therefore apparent, 1st, that partial chills, or the exposure of individual parts to low temperatures, may be and are felt very extensively even when the cold is not very severe ; 2nd, that the chilling of a single part, such as the hand or the foot, may cause a loss of temperature in all the other parts of the body, even far beyond what could have been pre sumed as likely or possible. These facts give a key to the right understanding of the immense influence which partial chills are capable of exercising on the state of the general health Of the effects of partial heating.—The hand being immersed in water heated to the tem perature of 34° It. (109° F.),rose one degree of the same scale, and the temperature of other remote parts not immediately exposed to the influence of heat were found to have risen in a corresronding degree. Whence follows this axiom,—that we cannot either raise or lower the temperature of any one part of the body without all the other parts of the being affected, and suffering a corresponding rise or fill in temperature, more or less according to circumstances. We may further presume from the comparison of these facts, that the body and its parts are liable to variations of temperature towards either extremity of the scale from the mean, much more considerable than are generally imagined. This latter fact will appear very evidently from the other inquiries which are now to engage our atten tion.
Effects of an excessively high or excessively low external temperature upon the temperature of the body.—Ilitherto we have only considered the changes in the temperature of the body pro duced by moderate degrees of external heat and cold. We now pass on to the examination of the effects caused by extreme external tempera tures, and first of those that follow from excessive heat ; designating by excessive heat any temperature that surpasses that of the human body. On a summer's day, the temperature of the air being 37°, 77 e. (100° F.), Franklin observed that the tempera ture of his own body was nearly 35°, 55 e. (96° F.). This fact, which is perhaps the first of the kind noted, is highly deserving of atten tion. It proves that man, and by analogy other animals,have a power of keeping their tem perature inferior to that of the air. As in the ob servation quoted there is no means of knowing what effect the excessive external temperature had produced upon the temperature of the observer, recourse must be had to other facts.
In numerous experiments made in England by Dr. Fordyce and his friends, and subsequently by Dr. Dobson, in which these experimenters exposed themselves to very high temperatures, which on some occasions exceeded that of boiling water, the heat of the body was never observed to rise more than one, two, three, or four degrees of Fahrenheit's scale at the utmost. As in these experiments the object especially proposed was to determine the degree of external temperature which the body could bear, all the attention which would have been desirable was not given to determine the tem perature of the body before, during, and after the experiments. This is an omission which is common to the experiments of For dyce and Dobson. The highest temperature of the body noted by Dr. Dobson is 102° F., but he does not mention the heat before the experi ment, nor does he notice the rate of cooling subsequent to its termination. The highest temperatures of the human body exposed to excessive heats ever observed, were remarked by Messrs. Delaroehe and Berger in their own persons. The temperature of M. Delaroche being 56° 56 e. (98° F.) increased 5° of the centigrade scale, by remaining exposed in a chamber the temperature of which was e. (176° F.). M. Berger, whose temperature was the same as that of M. Delaroche, gained 4° c. by remaining for sixteen minutes in the hot chamber at e. 5 F.). These experiments are liable to this objection,—that the temperature was taken in the mouth in an atmosphere of much higher temperature, which might have some influence in raising the ther mometer. To arrive at conclusions against which no kind of objection could be raised, Messrs. Delaroehe and Berger exposed them selves in succession in a box, out of which they could pass their head ; the hot air or vapour of the interior being prevented from escaping by means of a circular pad of soft napkins placed between the edge of the outlet and the neck. The temperature of the mouth, in this way, if it was increased, must be increased in consequence of a rise of temperature in the parts of the body included in the bath. After a stay of seventeen minutes in the bath, heated from 37°, 5 to 75 c. to F.), the temperature of Dclaroche's mouth rose 12 c. Under similar circumstances, the temperature of the bath being from 40° to 25 c. to 106° F.), the temperature of M. Berger's mouth increased 1°, 7 c. in the course of fifteen minutes.