Transcriber’s Notes
Punctuation and spelling were made consistent when a predominant preference was found in this book; otherwise they were not changed.
Simple typographical errors were corrected.
Ambiguous hyphens at the ends of lines were retained; occurrences of inconsistent hyphenation have not been changed.
The original book did not contain page numbers, so the ones used here are just for easier navigation.
Transcriber attempted to mute some unusually prominent checkered moire-like patterns in the background portions of the available illustrations, while preserving the important details of those illustrations.
In the table of Ranges:
Transcriber rearranged parts of the column headings, but “as follow” (singular) in the table’s title was printed that way in the original.
Transcriber transposed the rows and columns to make the table fit within narrow constraints imposed by some handheld reading devices and Project Gutenberg’s guidelines for Plain Text. (Rows originally were columns.)
The row heading “55 to 60°” was misprinted as “55 to 66°”; corrected here.