Page 9: closing quote mark inserted after "curious knot".

Page 45: "receptacles at C d" changed to "receptacles at c d".

Page 48: fig. 23 was printed upside-down in the source document.

Page 51: "the notches f or g in the bolt" changed to "the notches s or g in the bolt", cf. fig. 26.

Page 57: "the notches n n" changed to "the notches n n´".

Page 77: "shewn at a a in fig. 37" changed to "shewn at a´ a´ in fig. 37"; "3, 2, 3" changed to "3, 2, 3´".

Page 89: "T the third" changed to "T³ the third" cf. illustration.

Page 100: "piece of metal h p" changed to "piece of metal h h" cf. illustration.

Page 104: "ged" changed to "get".