648 THE POPULAR SCIENCE MONTHLY. 



Tylor, Lubbock, and De Mortillet — these have been the chief evolu- 

 tionary teachers and discoverers. But the use of the word evolution 

 itself, and the establishment of the general evolutionary theory as a 

 system of pliilosophy applicable to the entire universe, we owe to one 

 man alone — Herbert Spencer. Many other minds — from Galileo and 

 Copernicus, from Kepler and Newton, from Linnaeus and Tournefort 

 from D'Alembert and Diderot, nay, even, in a sense, from Aristotle 

 and Lucretius — had been piling together the vast collection of raw 

 material from which that great and stately superstructure Avas to bo 

 finally edified. But the architect who placed each block in its proper 

 niche, who planned and designed the whole elevation, who planted the 

 building finnly on the rock and poised the coping-stone on the topmost 

 pinnacle, was the author of the " System of Synthetic Philosophy," 

 and none other. It is a strange proof of how little people know about 

 their own ideas, that, among the thousands who talk glibly every day 

 of evolution, not ten per cent are probably aware that both word and 

 conception are alike due to the commanding intelligence and vast 

 generalizing power of Herbert Spencer. — Cornhill Magazine. 



WEATPIEK-PPwOGNOSTICS.* 



By the HON. EALPH ABEECEOMBY. 



FROM classic times, down to the commencement of this century, 

 it can hardly be said that this branch of meteorology made any 

 advance. Few, if any, new prognostics had been discovered, and 

 neither their physical explanation nor their meteorological significance 

 had been found out. But about eighty years ago some physical 

 explanations were given. It was found that the air always contained 

 a certain quantity of uncondensed vapor, and means were invented 

 for measuring this amount accurately. From this, the nature and con- 

 ditions of the formation of dew were discovered, and also that before 

 many cases of rain the air became more charged with vapor. This 

 latter fact gave the explanation of several rain-prognostics. For in- 

 stance, when walls sweat, stones grow black, and clouds form on hill- 

 tops, rain may be expected almost all the world over. 



But even when these reasons had been discovered, the science 

 flagged. A large number of rain-prognostics could not be shown by 

 any means to depend on an increase of moisture, and, as vapor can 

 not grow in the air, some explanation was needed to account for its 

 variable quantity. And even when, in a general way, the prognostic 

 had been explained, no clew whatever had been found for what we may 



•Abridged from "Weather," hy the ITon. Ralph Abercromby. " International Scien- 

 tific Scries," volume Iviii. New York : D. Appleton & Co., 1888. 



