706 



SCIENCE. 



[N. S. Vol. III. No. 71. 



The original negatives were carefully examined 

 by the physicists present, Prof. Eowland devo- 

 ting half an hour to their critical examina- 

 tion; and I do not think that the slightest 

 doubt was held, by any of the six physicists 

 present, of the completeness of the demonstra- 

 tion. 



I cannot conceive how Dr. Pupin, after an 

 examination of Eood's photographs, could difier 

 from, deny, or even doubt, the conclusions 

 reached by several of the most critical and ex- 

 perienced physicists of the country after their 

 examination of these photographs. 



Alfred M. Mayer. 



pseudo-science in meteorology. 



In the issue of Science for April 10th nearly 

 a full dozen columns of valuable space have 

 been devoted (under a rather misleading title) 

 to recording observations and opinions which 

 are to prove the absence of a favorable influence 

 of forest cover on meteorological phenomena 

 and especially on waterflow in the Western 

 Mountains. 



Since this subject has become not only one of 

 considerable scientific interest, but also of 

 great national importance, far-reaching eco- 

 nomic policies depending in part on the answer 

 which science or well sustained observation and 

 argument can give to the question, it may not 

 be out of place to devote further space to the 

 question in order to warn against the many 

 erroneous observations and fallacious conclu- 

 sions contained in the article referred to. 



I do not wish to oflTend the writer when I say 

 that by neglecting to sift more carefully the un- 

 tutored and too-often-prejudiced opinions and 

 notions of so-called ' practical ' men at the hand 

 of the established facts of science, physical, phy- 

 siological and meteorological, he has done 

 harm; for Tie has not only increased the accum- 

 ulations of ' practical ' or pseudo-science, to 

 which to be sure, many so-called ' scientists ' 

 contribute no small share, but he has also dis- 

 credited the sometimes valuable — when used 

 with discretion — observations of laymen with 

 those men of science who read with a knowl- 

 edge of the laws of physics and the facts of 

 meteorology before them. 



Sure enough meteorology, especially on the 



side of accurate measurements, is but poorly de- 

 veloped ; nevertheless there is much more real 

 knowledge in existence regarding many of the 

 physical processes and conditions involved, not 

 only qualitatively, but even quantitatively (as, 

 for instance, regarding the behavior of snows, the 

 evaporation of water, the transpiring of trees, 

 and the conditions which influence these and 

 the run-off and waterflow of rivers) than the 

 writer of the article is aware of, so that it is 

 not necessary to rely on opinions of ' practical ' 

 observers for these details at least. 



I wish, however, not to be understood as dis- 

 crediting in any way field observations and argu- 

 ment from them and as insisting upon accurate 

 measurements as the only basis for the explana- 

 tion of natural phenomena. On the contrary, 

 I am one of those who believe that many com- 

 plicated natural phenomena withdraw them- 

 selves for the present, i. e., with our present 

 knowledge and means, from accurate measure- 

 ment ; being results of complex and variable 

 conditions which we are not prepared to meas- 

 ure, we may only by careful, long continued 

 field observation and upon sound argument 

 from well-known physical laws come to conclu- 

 sions and determine relations qualitatively, 

 leaving quantitative measure of these relations 

 to be worked out in the future with improved 

 method. 



The present question, namely, that of forest 

 influences on meteorological phenomena, is one 

 of these, for in the first place we have as yet 

 neither instruments nor methods to measure 

 with any determinable degree of accuracy the 

 rainfall over a given area, much less the evap- 

 oration ; and even riverflow is not yet satisfac- 

 torily measured. And when it comes to the 

 many varying influences affecting these phe- 

 nomena quantitatively, we are entirely debarred 

 from speaking with assurance even as to 

 methods of determining them. 



It would require too much space to discuss in 

 detail the many erroneous statements and con- 

 clufflons contained in the article referred to and ■ 

 which any meteorologist or physicist can readily 

 discover. I shall have to confine myself to point- 

 ing out the fallacy of the main argument, 

 which appears the more important as it has 

 been advanced before by others with a flavor 



