ERRATA. 
First Paper, read February 1 , 1904. 
Page 185, line 8 from foot, for “£ = read “c = _^0.” 
dx dx 
,, 196, ,, 16 from top, for “ dcf ” read “ d-rf.” 
,, ,, ,, ,, ,, for “instead of 0” read, “ instead of 
Third Paper, January 23, 1905. 
Page 564, line 2 from foot, after “ speed” insert “ and smoothness.” 
Fourth Paper, read July 17, 1905. 
Page 1067, line 28, delete “whole.” 
,, ,, ,, ,, for “ the whole ” read “ a considerable part of the/ 
,, 1078, ,, 12 from foot, for “(115) ” read “(116).” 
