A number of transcription errors were found in the original book. As these were clearly not part of the Author's intention they have, as far as possible, been identified and corrected in accordance with the methods given by the Author. These corrections are listed here below with their locations and original text. In these notes the word 'natural' identifies a letter symbol occurring without a prime mark. Page viii: "189" corrected to "194". Page viii: "188" corrected to "192". Page xv, '=Real=' and '=Unreal=', or '=Imaginary=', Classes: "1½" corrected to "2". Page xix, Propositions beginning with "Some": "18" corrected to "19". Page xix, Rules: "19" corrected to "20". Page xix, The West and East Halves ...: "24" corrected to "23". Page xxi, The Proposition "All x are y" ...: was originally shown as occurring in page 34. Page xxii, And of three other similar arrangements: "37" corrected to "36". Page xxiii, The Proposition 'No xm exist': "43" corrected to "44". Page 060: "contruct" corrected to "construct". Page 094, Paper V: missing word "it" supplied. Page 111, #28: "No h are k-natural" corrected to "No h are k-prime". Page 111, #30: "No a are h-natural" corrected to "No a are h-prime". Page 111, #30: "No c are n-natural" corrected to "No c are n-prime". Page 123, #57 (d): "mortally offended if I fail to notice them" corrected to "mortally offended". Page 128, #34: "Some x-prime are y" corrected to "Some x-natural are y". Page 146, #30: "x_{1}m-prime_{0}" corrected to "x_{1}m-natural_{0}". Page 147, #32: "xm-natural_{0}" corrected to "xm-prime_{0}". Page 156, #18 (4/1): "be" corrected to "be-sub:zero". Page 156, #22 (5/1): "ch" corrected to "ch-sub:zero". Page 157, #23 (5/2): second underline corrected from single to double. Page 157, #23 (2/2): first underline corrected from single to double. Page 157, #23 (¶2): "h_{1}c" corrected to "h_{1}c-sub:zero". Page 157, #26 (5/1): "a_{1}c-natural_{0}" corrected to "a_{1}c-prime_{0}". Page 157, #26 (¶2): "e_{1}c-natural_{0}" corrected to "e_{1}c-prime_{0}". Page 157, #29 (8/2): first underline corrected from single to double. Page 161, #36 (4/2): "e'd-prime" corrected to "e'd-natural". Page 161, #39 (1/2): "c-prime+d" corrected to "c-natural+d". Page 161, #40: "a" and "b" interchanged. Page 161, #43 (1/1): "b-natural_{1}e_{0}" corrected to "b-prime_{1}e_{0}". Page 162, #52 (3/1): "h'k-prime_{0}" corrected to "h'k-natural_{0}". Page 163, #55 (3/2): "c'd-prime" corrected to "c'd-natural". Page 163, #57 (1/2): "h-natural+d'" corrected to "h-prime+d'". In the original book at the top of page 97, the following text occurred: [N.B. The numbers at the foot of each page indicate the pages where the corresponding matter may be found.] In accordance with the un-paged medium here this has been changed to: [N.B. Reference tags for Examples, Answers & Solutions will be found in the right margin.]