SCIENCE. 



Editorial Committek : S. Newcojib, Mathematics ; E. S. Woodward, Mechanics ; E. C. Pickering, As- 

 tronomy ; T. C. Mendenhall, Physics ; R. H. Thurston, Engineering ; Ira Rejisen, Chemistry ; 

 Joseph Le Conte, Geology; W. M. Davis, Physiography; O. C. Marsh, Paleontology; W. K. 

 Brooks, Invertebrate Zoiilogy ; C. Hart Merkiam, Vertebrate Zoology ; N. L. Britton, 

 Botany ; Henky F. Osborn, General Biology ; H. P. Bowditch, Physiology ; 

 J. S. Billings, Hygiene ; J. McKken Cattell, Psychology ; 

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



Friday, May 24, 1895. 



CONTEXTS: 



Variation of Latitude : J. K. Rees 561 



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

 Davis 568 



Gravity Measurements : Herbert G. Ogdex 571 



The Astronomical and Physical Society of Toronto: 

 Thomas Lindsay 573 



Correspondence : — 575 



The Hirers of Eden. J. William Dawson. 

 Color-a.tsociation with Numerals : E. S. Holden. 

 Unirersily of Kan.ias, State Geological Survey: 

 F. H. Snow. 



Scientific Literature : — 577 



Nehrling's Native Birds: C. Hart Merriam 

 Shaw's 3Iunicipal Oorernment : 3. S. B. Nernst's 

 Chemistry. Robert H. Br.vdburw Society 

 for the Promotion of Engineering Education. R. 

 H. T. Steam Poucr and Jlillworl- : R. H. T. 



Notes and News : — 581 



Jointx in the Vertebrate Skeleton : H. F. O. The 

 Preparation of Argun : .1. E. GiLPIN. Helion ; 

 Gravity Measurementi ; General. 



Societies and Academies : — .... 586 



Scientific Socitiirs of Washington : The Biological 

 Society of Washington ; Boston Society of Natural 

 History; Minnesota Academy of A^atural Sciences. 



New Books 588 



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

 for review sliould be sent to tlie responsible editor, Prof. J. 

 McKeen Cattell, Garrison on Hudson, N. Y. 



Subscriptions and advertisements should be sent to Science, 

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



VARIATION OF LATITUDE.* 

 The question is frequently asked, " How 

 can latitude change ? "' There are two waj's 

 obviously. First, we may imagine that a 

 portion of the earth slips on the surface of 

 the globe, due say to earthquake shock. 



* From a lecture before the Xew York Academy of 

 Sciences, April 29, 1895. 



Then if the movement of the mass has been 

 toward the equator the latitude of that 

 place is decreased ; if toward the pole of 

 the earth the latitude is increased. But 

 suppose that some forces at Avork on the 

 earth cause it to revolve about a new 

 axis, then we have at once a new equator, 

 and the latitudes of all points on the earth's 

 surface change except at those places where 

 the old and new equator intersect. 



If, for example, the earth's axis of revolu- 

 tion should be changed so as to pass through 

 this hall, the latitude would be changed 

 from a little over 40 degrees, as it now is, 

 to 90 degrees. There are changes no doubt 

 produced by the slipping of portions of the 

 earth's strata, but we know that these causes 

 are insignificant and local. The only w-ay 

 that latitudes could be made to change 

 throughout the tvorhl would be by changes in 

 the axis of rotation of the earth, thus chang- 

 ing the position of the equator. 



Are there anj' undisputed evidences of a 

 variation in the latitude of a place and is it 

 large ? 



To-day the evidence is overwhelming, 

 but the amount is small, so small, in fact, 

 that only the refined instruments of the 

 present day have been able to discover it ; 

 though now, that it is discovered, older ob- 

 servations show it. 



La Place, in his Mt'canique Celeste 

 (Tome v., p. 22), says " All astronomy de- 

 jjcnds upon the invariability of the earth's 



