SCIENCE. 



Editobial Committee : S. Newcojib, Mathematics ; R. S. Woodward, Mechanics ; E. C. Pickeeino, As- 

 tronomy ; T. C. Mexdexhall, Physics ; R. H. Thurston, Engineering ; Ira Remsen, Chemistry ; 

 J. Le Conte, Geology; W. M. Davis, Physiography; 0. C. JIaesh, Paleontology; W. K. Brooks, 

 Invertebrate Zoiilogy ; C. Hart Meeeiam, Vertebrate Zoology ; S. H. Scudder, Entomology ; 

 N. L. Brittox, Botany ; Henry F. Osborx, General Biology ; H. P. Bowditch, 

 Physiology ; J. S. Billings, Hygiene ; J. McKeen Cattell, Psychology ; 

 Daniel G. Brinton, J. W. Powell, Anthropology. 



Feiday, May 31, 1895. 



COA^TENTS: 



Oh the Elecirification of Air ; On the Thermal Con- 



dticthity of Hock at Different Temperatures : LORD 



KEL^^x 589 



A Dynamical Hypothesis of Inheritance : John A. 



Rydee 597 



Current Xotes on Physiography ( VII. ) : W. M. 



Davis 605 



Annual Meeting of the Chemical Society {London): 



W. W. R 606 



Correspondence : — 608 



Eaeclel's Monism : DAVID Stare Jordan. 



The Genus Zaglossus : ELLIOTT COUES. 

 Scientific Literature : — 610 



The Cambridge Natural History: W. H. Dall. 



Benton's Laboratory Guide of Chemistry: Vf. 



R. O. 

 Notes and Xeics : — 612 



The Hilmholtz Memorial ; The Geological Society 



of America ; XominatioM before the Soyal Society ; 



John A. Ryder; General. 



Scientific Journals : — 615 



The Astrophysieal Journal. 

 A'eic Books 616 



MSS. intended for publication and books, etc., intended 

 for review should be sent to the responsible editor, Prof. J. 

 McKeen Cattell, Garrison on Hudson, X. Y. 



Subscriptionsand advertisements should be sent to Science, 

 11 N. Queen St., Lancaster, Pa., or 41 East 49th St., New York. 



(1) 'OX THE ELECTRIFICATION OF AIR.'* 



§ 1. CoNTiNuors observation of natural 



atmospheric electricitj' has given ample 



proof that cloudless air at moderate heights 



above the earth's surface, in all weathers, 



*Two communications by Lord Kelvin, P.R.S., 

 to the Philosophical Society of Gla.sgow, meeting in 

 the Natural Philosophy lecture-room o( the Univer- 

 sity of Glasgow, March 27, ' On the Electrification of 



is electrified vrith very far from homogene- 

 ous distribution of electric densit}-. Ob- 

 serving, at many times from May till Sep- 

 tember, 1859, with mj- portable electrometer 

 on a flat open sea-beach of Brodick Bay in 

 the Island of Ai-ran, in ordinary fair weather 

 at all hours of the day, I found the difler- 

 ence of potentials, between the eartli and an 

 insulated burning match at a height of 9 

 feet above it (2 feet from the uninsulated 

 metal case of the instrument, held over the 

 head of the observer), to vary from 200 to 

 400 Daniell's elements, or as we may now 

 say volts, and often during light breezes 

 from the east and northeast it went up to 

 3,000 or 4,000 volts. In that place, and in 

 fair weather, I never found the potential 

 other than positive (never negative, never 

 even down to zero), if for brevity we call 

 the earth's potential at the place zero. In 

 perfectly clear weather under a skj* some- 

 times cloudless, more generally somewhat 

 clouded, I often observed the potential at 

 the 9 feet height to vary from about 300 

 volts gradually to three or four times that 

 amount, and gradually back again to nearly 

 the same lower value in the course of about 

 two minutes.^''- I inferred that these grad- 

 ual variations must have been produced by 



Air'; 'On the Tliermal Conductivity of Rock at Dif- 

 ferent Temperatures. ' Printed from proof sheets for 

 Nature contributed by the author. 



*' Electrostatics and Magnetism,' Sir William 

 Thomson. .\vi. U 281, 282. 



