HEAT AND LIFE. 145 
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 disease. Swammerdam, 
in the middle of the seventeenth century, seems to have 
been the first to have the idea of it. De Haén 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 day, thanks to the labors of Bouilland, 
Gavarret, Roger, Hirtz, and Charcot, in France; Biren- 
sprung, Traube, and especially Wunderlich, in Germany. 
These physicians were not content with proving that the tem- 
perature in illness rises several degrees ; they followed 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 con- 
stant types for each disease, which are modified in a reg- 
ular manner, according as the disease 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 
prognosis. In hemorrhage of the brain, for instance, the 
temperature falls to 36° or even 35°, while, in the attack 
that takes the form of apoplexy, it continues nearly at 38°. 
These two disorders, quite distinct in their treatment and 
cure, yet often give rise to a confusion, which the thermom- 
eter will hereafter permit us to avoid. Granular menin- 
gitis is distinguished from simple meningitis by the same 
method; in the former the temperature does not rise, not- 
withstanding the extreme rapidity of the pulse, but in the 
latter the thermometer marks 40° or 41°. 
In every case we see what advantage practical medicine 
may gain from the physical sciences, what precision and 
safety it attains by the employment of its means, in pro-| 
portion to the morbid symptoms. We may add that the 
