Page 52, par. 9, line 2.

“FP′F1P” should read “FP′f1P.”

Page 53, par. 14, line 11, insert after the word parabola

“indicated in Fig. 16 by RR1R′R′1 which also show that the parabola is the upper limit of the ellipse or lower limit of the hyperbola”

also for the word “and” substitute “then” in same line.

Page 54, par. 16, line 8, for “f1S2f2” read “f1xf2” and in line 9, for “f2Sf4” read “f2S2f4.”

Page 55, par 19, line 3, for “f1f2” read “f1f4,” and in line 4. for

“ca′1c1 and in line 5, for “xa1Q1C1” read “xa1Q1c”

in par. 20, same page, line 2, for “xS bisects P′S1Q′” read “xS1, bisects angle P′S1Q′”

same par., line 8, for “direction” read “directrix.”

Page 56, par. 24, line 1, for “CY and C1Y” read “cy and c1y,” and in line 3, for “YF” read ”yF,” par. 25, line 5, for “ScSx” read “SCSX,” and line 6, for “Sx” read “Sk,” and for “circle” read “radius.”