Human Physiology. 391 



follows cleanses and invigorates but the warm vapour relaxes 

 and weakens, and the air is loaded with impurities. Great 

 mischief may be done by these easy and agreeable applications. 



It is much better, as a rule for constant practice, and in the 

 cure of seriously diseased and debilitated conditions, to rely 

 upon the reactive power of the system the wonderful process 

 by which we ^generate vital heat. We are never to overtask 

 that power this is the first maxim in hydropathy but we are 

 to use it, train it, and by exercise gradually increase it. The 

 reactive power of the patient his ability to get warm after a 

 cold bath is the fulcrum of the lever of cure. It is the 

 measure of the possibility of cure. When we use artificial 

 heat we weaken the reactive power. In many cases, the gain 

 may be greater than the loss; but in others, and the more 

 important ones, the loss is beyond compensation, and we 

 have to husband the vital force on which cure depends with 

 the greatest economy. 



If artificial heat is, in most cases, to be avoided, there is 

 even greater and more immediate danger from excess of cold. 

 Heroic, or careless, slap-dash practitioners order long cold 

 douches, or long deep or running sitz baths, to patients of low 

 reactive power, and they come out blue, constringed, weak, 

 shivering, miserable, and exhausted. In every case, the patient 

 should come out of a bath in a red glow, or get warm with rub- 

 bing, and remain so. An after-chill shows that the bath has 

 been too much for the reactive power. The patient should go 

 into every cold bath warm from exercise or rubbing, and come 

 out warm, or readily get warmed by exercise and friction, and 

 the reaction of a quickened circulation. 



It is difficult to explain the invigorating effects of cold. We 

 speak of cold air as bracing. Franklin speaks highly of the 

 cold-air bath, and found the exposure of his naked body to it 

 very invigorating; but the effect of cold water is much more 

 rapid and powerful. We test it by dipping a hand or foot into 



