CORRESP ONDENCE. 



499 



CORRESPONDENCE. 



ALLEGED FALLACIES OF SCIENCE-CAU8E 



AND EFFECT MODES OF FORCE. 

 To the Editor of the Popular Science Monthly: 

 TAR. JOHN W. DRAPER'S "History of 

 -L-' the Conflict between Science and Re- 

 ligion" should be read by every searcher 

 after truth. But Dr. Martineau's address 

 in London, last fall, on " Religion as affected 

 by Modern Materialism," considered in con- 

 nection with Dr. Draper's book, portends 

 danger to the dogmatic assertion of mere 

 hypotheses, or guesses, as scientific facts. 

 Enlightened people are fond of sensation 

 as a pastime, but, in the serious and des- 

 perate conflict which is surely approaching, 

 they will accept neither superstition nor 

 sophistry, but only mathematical truth or 

 pure logic. Scientific imagination, useful 

 in research, should not be allowed to cul- 

 minate in illogical speculation. Phenom- 

 ena are effects : and not their causes, but 

 only their correlates or conditions under 

 which they occur, lie in the field of physical 

 science. 



Physical force is not the cause of physi- 

 cal action. Specific modes of force have no 

 physical existence, but are only in thought 

 correlatives to phenomena. Gravity is not 

 the cause of tbe persistent movement of 

 cosmical bodies, nor of their relative posi- 

 tions to each other, nor is it a physical 

 " thing ; " it is only one of the many corre- 

 lates in thought, of the ever-changing rela- 

 tive positions of these bodies. 



Physical force or pressure has no gen- 

 eralized mechanical equivalent. Like quan- 

 tities of mechanical effect, due to like quan- 

 tities of any mode of force, are limited to 

 exact conditions. 



The fact that mere physical force or 

 pressure is not the cause of motion, and has 

 no quantitative equivalent in mechanical 

 effect, is mathematically demonstrated thus : 

 Under the gravity or pressure of the at- 

 mospherefifteen pounds to the inch 



water has a velocity of forty feet per sec- 

 ond, and steam, or other gas of like den- 



sity, a velocity of 1,600 feet. Hence, con- 

 sidering the relative velocities and masses, 

 the mechanical effect observed with refer- 

 ence to the gas is forty times that with 

 reference to the water, both substances acting 

 under the same pressure during the same 

 time. (Space, never having been alleged to 

 be a cause, is purposely neglected in this 

 calculation. As a correlate of phenomena, 

 it will form the subject of a future com- 

 munication.) These varying effects obtain 

 whenever unlike masses move under like 

 qualities of constant force. Therefore, as 

 cause equals effect, the mechanical effects, 

 proportional to mass, being quantitatively 

 different under the same force, they cannot 

 be caused by the pressure or force under 

 which they act. 



Hence, that scientific imagination which 

 treats modes of force as causes, and from 

 this hypothesis, and exactly conditioned 

 experiments, generalizes the quantitative 

 equivalent effect of any one mode as the 

 "mechanical equivalent of heat" and 

 from similar hypotheses calculates the den- 

 sities, temperatures, etc., of other worlds 

 than ours, is not in accordance with mathe- 

 matical demonstration, and is, therefore 

 a delusion. "Promise and potency" are 

 causes, and, as Prof. Tyndall very properly 

 says, are discerned in matter ; and, being 

 absolutely known, they are not susceptible 

 of proof. But their effects, being only ob- 

 served, and therefore conditioned, are sus- 

 ceptible of both proof and prediction from 

 knowledge of the several conditions under 

 which they arise. Pure science adduces 

 not the causes, but only these conditions 

 of phenomena. 



The times portend a crisis in one of Mr. 

 Herbert Spencer's rhythms which has long 

 been setting in, laden with sophistry, mis- 

 called expediency, and general demorali- 

 zation. Let pure science, resolutely, but 

 carefully, take advantage of its ebb. 



A. Aknold 

 Tenafly, N. J., December 28, 1874. 



