Inconsistencies in spelling and hyphenation have been retained. Punctuation has been normalized.
The following errors have been corrected:
- p. 46 "two or three hundreds" fixed to "... hundred"
- p. 51 Chapter VII: fixed numbering of topics
- p. 72 carelessless → carelessness
- p. 85 change A1 to A´ to match the illustration
- p. 87 graps → grasps
- p. 88 "betwee nthem" → "between them"
- p. 90 fixed period instead of comma
- p. 90 graps → grasps
- p. 119 removed redundant "of"