Editorial note

The manuscripts of the Introduction and Appendices A, B, and C are transcribed below with almost all the changes due to the publisher's “house style” imposed, as in the use of capitals in the title. More substantial changes which Russell made as corrections to the printer's proof sheets are indicated in footnotes as “‘…’ becomes ‘…’”. Russell struck out some material with a single line (reproduced here in the text as deletions) and sometimes added some material above the line, and that is indicated as well. These insertions, usually above the line with a caret to indicate their position, are inserted in the line with ‘⌊’ and ‘⌋’ around the inserted material, as follows:⌊insertions⌋. A sequence below such as “Given p and p|(q|r), we can infer ⌊r⌋ q” indicates that the letter q was deleted and changed to r probably immediately after it was first written. Footnotes in the manuscript are indicated by a line across the page but are presented here as they appear in print. The printed Introduction begins on page xiii, indicated below in parentheses. Subsequent page numbers are inserted in the text where the page begins in the printed version. The number in the manuscripts (“foliation”) is reproduced in italics in the upper right hand corner of the material from each page. When Russell reused a leaf, giving it a new number, this is indicated in a footnote.