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THE POPULAR SCIENCE MONTHLY 



CORRESPONDENCE. 



A COMPLAINT ABOUT THE MONTHLY. 



Messrs. Editors. 



WILL you permit a brief criticism of 

 your selections for " The Popular 

 Science Monthly " ? My appreciation of the 

 journal is sufficiently indicated in its recep- 

 tion and careful reading from the time it 

 was begun. I have for some fifty years 

 tried to do my own thinking not so self- 

 sufficiently, however, that I am not very 

 glad to get what true help I can from other 

 thinkers. 



I have been attracted to " The Popular 

 Science Monthly " by the evident desire and 

 purpose of its conductors to give a fair 

 hearing to all views, pro or con, on any sub- 

 ject of general scientific interest. There is 

 one, however, now before the world which, 

 in importance to the whole human family, 

 can be assigned to no second place, which, 

 in my view, you treat in a very partisan 

 manner. I refer to the Harmonial Philoso- 

 phy, Spiritualism, or whatever it may be 

 called. This question, whether evolving 

 truths of the deepest importance to human- 

 ity, or a species of insanity, delusion, or im- 

 position, demands attention and discussion ; 

 for millions of people are to-day affected 

 more or less by its phenomena and teach- 

 ings, and it is spreading with a rapidity un- 

 realized by the indifferent observer. From 

 its first opening with the Fox girls near 

 Rochester, New York, to the present, I have 

 observed it closely, and often under very 

 favorable circumstances. To endorse it en 

 masse would to me be folly ; to utterly ig- 

 nore it, equally so. 



I am fully satisfied that there are great 

 and most important truths involved in the 

 subject, which demand elimination from 

 what may be accompanying rubbish. Now, 

 when you select for " The Popular Science 

 Monthly " articles all, or nearly so, on one 

 side of this question, and from men like 

 Hammond, Beard, Gairdner, Trowbridge, 

 etc., you leave the path of true science for 

 that of the partisan. 



To me, as well as several other readers 

 of the journal with whom I have communi- 

 cated, a fair discussion of this subject would 

 not only add interest, but remove a present 

 offense. You might lose some bigoted and 

 fossilized readers, but you would gain an 

 equal if not larger number of the less prej- 

 udiced. 



A. L. Child, M. D. 



Plattsmotith, Nebraska, May 30, 1879. 



"WASTED FORCES." 

 Messrs. Editors. 



In an article on " Wasted Forces " by 

 William H. Wahl, Ph. D., in "The Popu- 

 lar Science Monthly" for July, 1879, I note 

 some remarkable statements in that part 

 of the article which deals with the effi- 

 ciency of steam-engines. The writer seems 

 to have ignored the principal cause of 

 wasted heat in the steam-engine, viz., the 

 efficiency of the fluid, and to have aug- 

 mented the other losses in order, apparent- 

 ly, to account for the low efficiency of the 

 whole machine. In doing this he has given 

 figures, which not only leave wrong impres- 

 sions in the minds of those not familiar with 

 the subject, but he makes opportunities for 

 improvement seem far greater in some di- 

 rections than they are. I do not care to 

 call in question the fifteen per cent, which 

 Mr. Wahl gives as the greatest efficiency 

 yet obtained from steam-engines, but in 

 locomotive-engines, with which I am most 

 familiar, five per cent, will more nearly rep- 

 resent the efficiency of average perform- 

 ance. Granting that fifteen per cent, may 

 be obtained in the most economical engines, 

 it is to Mr. Wahl's method of accounting for 

 the loss of eighty-five per cent, that I ob- 

 ject. On page 292 one reads : " For by far 

 the greater portion of this eighty-five per 

 cent, of wasted power is chargeable directly 

 to the steam-boiler, and but a comparative- 

 ly small proportion thereof to the engine." 

 And again, on page 293 : " Summing up 

 all the items of loss in the steam-generator, 

 it is probable that with the best forms of 

 boiler which it has been possible to con- 

 struct, not more than twenty-five per cent, 

 of the theoretical thermal effect of the fuel 

 is utilized in the generation of steam ; and 

 of this twenty-five per cent., from five to 

 ten per cent, is lost somewhere on the 

 passage of the steam from the boiler to 

 and through the engine by condensation in 

 steam-pipes, and friction of the machinery, 

 leaving us but fifteen or twenty per cent, 

 actually realized in practice." As a mat- 

 ter of fact I have repeatedly observed from 

 fifty to fifty-five per cent, of the total theo- 

 retical number of heat-units obtainable from 

 the complete combustion of bituminous coal 

 transferred to the water and steam in the 

 boiler from locomotive fire-boxes, in which 

 the proper burning of coal is far more diffi- 

 cult than in stationary fire-boxes, or those 

 witli natural draught and ample room ; in 

 such fire-boxes as last mentioned, coal is 



