Here then is a complete counter-part, or rather prototype of the HYDRO-SUDO-PATHY, as already described. But there is one process which will appear incredible to most people—that of procuring perspiration by means of blankets wetted with cold water. Let us see whether an illustration of this may not be found. Every one who has read the Waverly Novels must have been struck with the singular practice pursued by some Highlanders (outlaws I think) who were obliged to pass many winter nights unsheltered on the freezing mountains. When they were desirous of sleeping, they dipped their plaids in the freezing water of the nearest pool or stream, and, wrapping themselves in this dripping and gelid mantle, went quietly to sleep! So long as the plaid kept wet, the Highlander kept warm, and slept soundly; but the moment it got dry, the man was awoke by the cold, and proceeded to the brook or stream to saturate his bed-clothes again with cold water. Here we have the prototype of the German process described in the case of the girl with inflamed lungs. By what process of _reasoning_ the Silesian peasant and the Celtic mountaineer, arrived at the knowledge of these curious facts, would be difficult to imagine. There was probably no reasoning in either case, but chance, observation, and experience. It is sometimes more easy to explain a phenomenon when discovered, than to arrive at it by any process of reasoning previously. The wet plaid by confining the animal heat of the Highlander, soon occasioned a warm atmosphere around his body, which kept him comfortable. But as soon as the plaid got dry and its texture _pervious_, then the animal heat rapidly escaped, and the feeling of cold dispelled sleep. In the case of pneumonia related by Dr. Weiss, the wet blanket was surmounted by several other blankets, which effectually prevented the escape of animal heat, which would soon accumulate and eventuate in perspiration. In such cases there would be a chill at first, succeeded by reaction, heat, and transpiration. We see this exemplified every day, where cold lotions are applied to an inflamed part. If the clothes are defended from the external air, they soon become warm, and form a fomentation—whereas, if exposed to a current of air, they will almost freeze the part by evaporation. Dr. Weiss’s patient would never have perspired, if the wet blanket had not been covered by dry ones. We are now prepared to glance at some other cases recorded by the professors of hydropathy.