1895. | NEW YORK ACADEMY OF SCIENCES. 75 
while rational and simple on the face of it, is inapplicable be- 
cause it is the areas of sedimentation, subsidence and ‘ over- 
loading ” that later on are upheaved in the mountains, and this 
apparent contradiction is the great difficulty. He also referred 
to the measures of rigidity of the crust, to the remarkable local- 
ization of the yielding along narrow lines when it did come, and 
to its relatively short duration. He asked Professor Woodward 
to touch on the slowing up of the revolution of the earth and 
the consequent readjustment of the spheroid to the lessening of 
centrifugal 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 mountain ™ 
protuberances as measures of rigidity, and yet this must be 
qualified by the statement that according to isostasy and to re- 
cent pendulum observations they appear to be somewhat lighter 
under the surface. As to the slowing up of rotation and loss of 
centrifugal force, the idea was an important and valuable one, 
but it did not appear to be sufficient to account for the results. 
Professor Rees referred to the recent observations on changes 
in latitude made under his direction, and to certain factors that 
entered into the calculations which would throw light on the 
question. 
Professor Hallock brought up the recent results of experi- 
ments on the gyration of liquids as bearing on the question and 
proving that a fluid set in rapid rotation continues to gyrate 
long after the enclosing vessel ceases. The curious results ob- 
tained at the Waterville arsenal in the great testing 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 sub- 
stances became, 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 
