February 15, 1895.] 



SCIENCE. 



195 



cooling must be attributed the principal 

 motive force. The main criticism raised 

 against it is its insuflieiency, but George 

 Darw^in has shown that as a cause it can be 

 mathematically shown to be able to produce 

 results at least of the same order as those 

 observed. In the sj)eaker's estimation it is 

 probably sufticient, although the heat ra- 

 diated is a very difficult thing to measure 

 in a reliable way. Our data are all from the 

 continents, and they have not been obtained 

 in sufficient quantity. The oceanic areas 

 are necessarily unoliserved. 



In discussion Professor Kemp stated that 

 attention had been naturally been drawn to 

 the interior of the earth in the endeavor to 

 explain, first of all, the contrasts of the con- 

 tinental elevations and the oceanic abysses, 

 and secondly, the crumplings, foldings and 

 faults of mountainous regions. Herschel's 

 explanation, while rational and simple on 

 the face of it, is inapplicable because it is 

 the area of sedimentation, subsidence and 

 ' overloading ' that later on is upheaved in 

 the mountains, and this apparent contradic- 

 tion is the great difficulty. He also referred 

 to the measures of rigidity of the crust, to 

 the remarkable localization of the yielding 

 along narrow lines wlien it did come, and to 

 its great effects and relativelj' short dura- 

 tion. He asked Professor "Woodward also 

 to touch on the slowing up of the revolution 

 of the earth and the consequent readjust- 

 ment of the spheroid to the loss of centri- 

 fugal force, an idea advanced some years 

 ago by W. B. Taylor. 



In reply Professor "Woodward admitted 

 that the questions were old and very difficult 

 ones, and that for the mountains he had no 

 explanation to advance. He spoke of the 

 mountainous protuberances as measures of 

 the rigidity, aiul yet this must be qualified by 

 the statement that according to isostas}- and 

 to recent pendulum observations they ap- 

 pear to be somewhat lighter under the sur- 

 fiice. As to the slowing up of rottitiou and 



loss of centrifugal force, the idea was an im- 

 portant and valuable one, but it did not ap- 

 pear to be sufficient to account for the re- 

 sults. 



Professor Rees referred to the rt'cent 

 observations on changes in latitude made 

 under his direction, and to certain factors 

 that entered into the calculations wdiich 

 would thrown light on the question. 



Professor Hallock brought up the recent 

 results of experiments on the gyration of 

 liquids as bearing on the question and prov- 

 ing that a fluid set in rapid rotation con- 

 tinues to gjrate long after the enclosing 

 vessel ceases. The curious results obtained 

 at the "Waterville arsenal in the great test- 

 ing machine were also cited. The attempt 

 was made to burst a cast iron cylinder by 

 forcing into it, through a three-sixteenth of 

 an inch hole, paraffine and tallow. But it 

 was found that both these substances be- 

 came, under high pressures, more rigid than 

 steel and could not be driven through the 

 hole. 



Prof Britton asked Prof "Woodward if 

 the amount of heat radiated per annum 

 could be quantitatively expressed, and in 

 reply Prof. "Woodw-ard said it is computed 

 £i-om very meagi-e data to be enough to melt 

 a layer of ice 5 to 7 mm. thick over the 

 earth's surface. The chairman. Prof E. P. 

 Whitfield, in closing the tliscussion called 

 attention to the fact that the submarine 

 crumpling and upheaval were not well 

 known nor often taken into account, and 

 yet the}- probably far exceed all that we see 

 on the continents. 



The discussion will be continued at the 

 meeting of the Section, February 18. 



J. F. Kemp, Recording Secretary. 



SCIENTIFIC JOURNALS. 

 AMERICAN JOURNAL OF SCIENCE, FEB. 



Relation of Gravity to Continental Elevation: 

 By T. C. Mendenhall. 



