336 



SCIENCE. 



[Vol. I., No. 12. 



final statement of the case of two floating bodies 

 apparently comes to this : that the concave meniscus 

 " acts upon both bodies toward a common centre of 

 concavity," and also exerts upon these bodies a ver- 

 tical downward force equal to the weight of the water 

 sustained. If this is Professor Leconte's conception 

 of the case, I do not feel to blame for not under- 

 standing him at first. 



If, on the other hand, he supposes the weight of 

 the water to be applied to the floating bodies, not by 

 means of the surface-film, but in some other manner, 

 it was, I submit, incumbent upon him to explain how 

 and where he supposed it applied. 



So much in explanation and support' of my criti- 

 cism of Professor Leconte's original statement. It is 

 now, perhaps, worth while to examine a little further 

 his final statement, as quoted above, beginning, 

 "Indeed, it is obvious." Does not this statement, 

 taken in connection with his first statement, also 

 quoted above, lead directly to the conclusion that he 

 supposes a column of water may be sustained between 

 two bodies by capillary action without exerting any 

 resultant downward force upon these bodies? — that, 

 in short, the water is pulled up without any result- 

 ant tendency to pull the bodies down ? 



I have written thus at great length, and with per- 

 haps unnecessary statement of elementary principles, 

 because I intend this letter to be final upon my part. 

 Edwin H. Hall. 



Harvard college, Cambridge, Mass. 



THE INDIANA GEOLOGICAL REPORT.* 



Indiana : department of geology and natural history. 

 Eleventh annual report (1S81). John Coliett, state 

 geologist. Indianapolis, State, 1882. 401 p., 

 55 pi. 8°. 



This volume contains some interesting sci- 

 entific and economic matter, partly original,, 

 but largel}' in the form of useful reprints of 

 tilings not accessible to the people whose needs 

 it is meant to serve. 



There is, in the first place, the rejDort of a 

 ■well-made inquiry into the transverse strength 

 and elasticity of building-stones, piincipallj' of 

 the excellent oolite of the St. Louis division 

 of the sub-carboniferous limestones. The point 

 is well made, that the resistance of hammered 

 blocks of stone to compressive strains is veiy 

 much less than that of sawed masses, owing 

 to the unseen disintegration of the mass pro- 

 duced by the blows of the hammer. There is 

 also the noteworth}' suggestion, that the modu- 

 lus of resistance to compression may be ap- 

 proximately estimated by the ' ring ' of the 

 mass when struck. 



There are several countj' reports which have 

 no general value. They contain some ven- 

 turous discussions of the extremely difficult 

 problems connected with the work of the last 

 glacial period in the Ohio valley. Glacial 

 rivers, glacial lakes, ice-fronts, and all the 

 other machinery of that time, are handled with 

 charming ease and dexterity-. We only hope 

 the observers will work past this first transpar- 



ent stage of the inquirj^, and find how bej'ond 

 imagination hard is this task of explaining the 

 work of the ice-time, and how useless are such 

 vague conjectures unfortified hy the amplest 

 delineation of facts. 



In the report of Mr. Coliett on Shelbj' 

 county, we find the very interesting statement, 

 that, in several wells sunk in one part of this 

 count}', heated waters have been struck within 

 fift}' feet of the surface. Nothing is given 

 concerning the amount of flow of these waters 

 or their chemical composition, nor are vce told 

 anything concerning the goodness of the ther- 

 mometers with which the observations were 

 m'ade, — all very important points. We onlj' 

 have the statement that the water was not 

 potable, and that its temperature was as high as 

 86° F. As this district is below the level of the 

 carboniferous series, it ma}' not be reasonable 

 to suppose that the temperature is due to the 

 decomposition of iron pj'rite, the only consid- 

 erable known sources of that mineral available 

 in this district being in the coal-measures. It 

 is perhaps more probable that the temperature 

 is due to downward penetration and return of 

 water in a system of faults, which we must 

 suppose to extend to a great depth, though 

 they do not manifest themselves on the surface. 

 If the waters are highlj' sulphurous, the origin 

 of the heat in the decomposition of pj'rite is 

 the most probable ; if thej' are not sulphurous, 

 their source must be sought in faults. ■ The 

 question merits a careful stud}'. 



Two hundred pages of tlie text, and thirt}'- 

 two of the plates, are reprints of James Hall's 

 Waldron fossils, with some emendations, in- 

 cluding four new plates. 



Dr. Charles A. White gives a series of plates 

 and descriptions of fossils from the collection 

 of Mr. J. W. Van Cleve. Hall's monograph is 

 well known to but few. It was originally 

 published in the twenty-eighth report of that 

 mj'sterious bod}' corporate, the regents of the 

 university of New York. This is the first pub- 

 lication of it that could have been of any use 

 to Indiauian students. 



The species described by Dr. White are 

 chiefiy corals, and are not regarded by the 

 author as new species. This part of the work 

 is essentially of local interest. All the species 

 have been better set forth before, but never in 

 a form so accessible for the dweller in the 

 rural parts of Indiana. 



Although there is not much that is original 

 in this book, it very likely has a higher meas- 

 ure of utilit}- for the people who pay for it 

 than many a survey report that has better 

 served the purposes of pure science. The old 



