37 o THE POPULAR SCIENCE MONTHLY. 



The powers and possibilities of protoplasm may be crudely com- 

 pared to those of steam, the expansive property of which may be 

 observed in a simple apparatus for the grinding of coffee, for example, 

 or in the operations of a magnificent Corliss engine, by which all the 

 complicated machinery of an entire Exposition may be set in motion. 

 The steam has precisely the same properties in the two cases, but the 

 resulting forces differ in proportion to the complexity and multiplicity 

 of the relations of the parts of which the different mechanisms are 

 respectively composed. 



In the study of the highly complex mechanism, the human body 

 which constitutes the study of medicine all the powers and proper- 

 ties of matter must be duly considered and taken into account, for all 

 are concerned in the production of its forces and in the performance 

 of its functions ; not one is violated or turned out of its natural course, 

 but all combine in a harmony more complete than is manifested by 

 any other known combination of materials and forces. Heterogene- 

 ousness the most extreme, complexity the most intricate, actions and 

 reactions the most delicately balanced, all unite, in the play of the 

 forces of the body, in the production and manifestation of its varied 

 powers. 



The study of science in any of its numerous departments is intrin- 

 sically elevating and ennobling if it be pursued in the true scientific 

 spirit, viz., in the desire and search for truth for truth's own sake ; and, 

 while the pursuit of medicine has its practical side in preparing its 

 votaries for the service of suffering and sick humanity perchance for 

 making the blind to see, the deaf to hear, and the lame to walk it 

 also broadens and enriches their own individual characters and lives, 

 since it leads them into the green pastures by the still waters of the 

 eternal truths of nature, at the same time bringing them into the still 

 higher experiences of sympathy and charity toward all mankind. 



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THE MECHANICS OF INTEKMITTENT SPKHSTGS. 



By Dr. OTTO WALTEEHOFEE. 



THE springs called thermal springs are found in all latitudes, at 

 various elevations above the sea, and in most of the geological 

 formations. The word thermal does not, however, denote a spring of 

 any particular degree of temperature, and is far from signifying that 

 the springs to which it is applied are all equally warm ; for any spring 

 is thermal, the water of which is warmer than the mean annual tem- 

 perature of the place where it occurs. In the equatorial regions, where 

 the mean annual temperature is about 80, a thermal spring should 

 have a temperature of about 85, while in the northern parts of the 



