ERRATA. 
Page 198, Note J, “ stated ” should be “ statical.” 
Page 204, Note # , p. 4. should be 195. 
Page 204, Note f, Note I., p. 15. should be 206. * 
Page 206, Note # , “ Williams ” should be “ Willans,” 
Page 210, Note f, p. 16. should be 207. 
