I love these types of books that give a brief (1 paragraph) and diagram about some machine used in the past (1700's, 1800's, 1900's).  I have probably 8 other books of this kind.  This book had some devices, that I had not seen before.  It does not give the details of size, shape, how to make, how to use. Just a diagram.<br><br>If you like mechanical devices, this is a good book for you.  If you are looking for plans or directions on how to build mechanical devices this isn't the best source.