4 io THE POPULAR SCIENCE MONTHLY. 



bations of from half a degree to a degree, during three or seven days, 

 at the end of which time the disorder lias run its course. When the 

 temperature gradually rises after the third day, a fatal result may he 

 expected. Persistent heat in that case is the precursor of death. 

 Eruptive fevers, like small-pox, scarlatina, and measles, present very 

 important phenomena of heat. In these heat begins with the attack 

 of the malady, and increases till the cutaneous eruption occurs. It 

 keeps up at a maximum, which reaches 42^ (in scarlatina), till the 

 eruption is complete, then it begins a declining course, variable with 

 the phases of the eruption, which finishes either with scaling off as in 

 scarlatina, or suppuration as in small-pox. And the temperature rises 

 also in several surgical aifecticns, bringing on a more or less inflamed 

 and feverish condition. This is observed in wounds, and generally in 

 every kind of traumatism, in tetanus, aneurisms, etc. In the case of 

 strangulated hernia and of burns, and in most cases of poisoning, on 

 the other hand, it declines in a remarkable way. 



Very plainly this rising and falling of animal warmth in diseases 

 can only be attributed to a corresponding state occurring in the 

 energy of respiratory combustion. We do not yet exactly know the 

 cause of these variations ; that is, the mechanism by which the mor- 

 bid influences stimulate or check the active production of heat. Some 

 physicians see in it the effect of fermentations occasioned in the blood 

 by certain microscopic beings, such as bacteria and vibriones, which 

 may perhaps be supposed to be the fact in most febrile maladies. 

 Others assume that, in local inflammations, it is the inflamed organ 

 which communicates heat to the whole body, as a furnace does in a 

 confined space. To others the disturbance seems rather to have a ner- 

 vous origin, since the nerves, as we have seen, are the regulators of 

 thermic action. 



The use of the thermometer is the only exact method of measuring the 

 temperature in diseases. Swammerdam, in the middle of the seventeenth 

 century, seems to have been the first to have the idea of it. De Haen 

 and Hunter, in the last century, used it in their medical practice, but 

 its employment at the sick-bed has really only come into importance 

 in our own day, thanks to the labors of Bouilland, Gavarret, Roger, 

 Hirtz, and Charcot, in France ; B'arensprung, Traube, and especially 

 Wunderlich, in Germany. These physicians were not content with 

 proving that the temperature in illness rises several degrees ; they fol- 

 lowed the variations of the thermometer day by day, hour by hour, 

 in the different phases of the pathologic movements. They discovered 

 that the curves of these oscillations furnish constant types for each 

 disease, which are modified in a regular manner, according as the dis- 

 ease has been left to itself or treated by one or another medicine. By 

 the study of these pathologic curves of heat the course of diseases 

 may be followed, and valuable indications noted in diagnosis or prog- 

 nosis. In haemorrhage of the brain, for instance, the temperature falls 



