effect of its high temperature on him was to quicken his pulse a little, and produce a gentle perspiration. Fire, indeed, appeared his element, and so perfectly could he control and master it, that he received almost by acclamation the title of “the Fire King.” Human greatness, however is but transitory, and even the laurels of the Fire King were wrested from him by the envious doctors of the metropolis, who wished him to drink prussic acid of _their own manufacture_, an invitation which he very politely and prudently declined. But though on this account suspicion was cast on his pretensions as a poison-drinker, yet his reputation as a “Fire King” remained untarnished. He could continue in an oven heated above the temperature at which water boils, and he did so daily. There was no trick in this performance, for he used to take raw eggs into the oven with him, and send them out to the company, well done by the heat of the place alone. It was thought no man could imitate his example. But however wonderful the feats of this conjuror may appear to persons unacquainted with science, and while it must be confessed they were performed with an appearance of daring and temerity which certainly entitled the exhibitor to some degree of praise, yet his performances were merely a striking illustration of the power which every individual possesses of regulating the temperature of his own body; and there was scarcely one person of his audience but might himself have been the exhibitor, with very little training and with very little courage. Of all the functions of the human body one of the most wonderful is that by which it maintains in every climate, and in every variety of season, an almost equal temperature. It would appear to be necessary for the due performance of the vital functions that this temperature should never suffer any great degree of variation, and nature has accordingly provided the means by which, when exposed to cold, the body can generate heat; and when exposed to heat, so reduce its temperature that no inconvenience shall result. Before considering the manner in which these very different though equally necessary results are produced, it will not be uninteresting to notice a few examples of the power of endurance shown by human beings and the lower animals in regard to extremes of temperature. In another paper we will endeavour to explain the cause.