WILLIAM PERREL. 3S9 



are seen to have been characterized by a preference for inductive 

 methods, and the other two by a greater use of deductive methods. I 

 do not mean to imply that any one of these able men was so unbal- 

 anced as to be illogical in his studies, and follow only one method to 

 the exclusion of the other ; but that they had natural leanings one 

 way or the other, as most men have. The greater fund of mate- 

 rial embodied in our modern weather maps was iitly used by Loomis, 

 much in the same manner as Redfield had used the scattered records 

 of storms half a century earlier; the greater accuracy of the results 

 gained by Loomis is a measure of the greater fulness of material for 

 investigation, rather than au indication of a difference between the two 

 men. On the other hand, much as Espy was led to his understanding 

 of storms through a mental invention, a theory, ingeniously based 

 on physical laws, so Ferrel was led to a generalization concerning the 

 circulation of the entire atmosphere from a full appreciation of the 

 laws of motion, rather than from any acuteness of observation. The 

 consequences deduced from his theory far outstripped the knowledge 

 of his time and profoundly affected the further progress of the science. 

 His earlier studies of the tides were carried on in the same way. His 

 work always illustrated the power of the mind to conceive and com- 

 bine relevant facts with a view to explaining them legitimately, yet. 

 with little recourse to direct observation or experiment for himself. 

 It is noticeable in his autobiographical sketch that Ferrel seldom makes 

 mention of observation or experiment as holding a significant part in 

 his early or more mature studies. As a boy be played with geometri- 

 cal problems, spending weeks together over a single one ; the diagrams 

 which he scratched on the barn door with the prong of a pitchfork 

 were only so many convenient records of the conditions of his prob- 

 lems; but he tells nothing of making mechanical toys, which hold so 

 large a place in the youth of experimental philosophers. When only 

 fifteen years old, he struggled over the prediction of eclipses, but the 

 facts he dealt with were supplied chiefly from Fanner's Almanacs ; nor 

 did this study seem to awaken in him a wish for means of investigation 

 with astronomical instruments, but only a keen desire for more books. 

 It is sad to think how limited were his opportunities in his youth. 

 He was born in Bedford (now Fulton) County, Pennsylvania, on Jan- 

 uary 29, 1817. When he was twelve years old, his father moved across 

 the narrow arm of Maryland into Virginia, anil there the. boy went to 

 school two winters, the schoolhouse being a rude log cabin, with oiled 

 paper instead of glass in the windows. His last school teacher took 

 him through arithmetic and the English grammar. lb- was too ditli- 



