E-text prepared by Chris Curnow, Joseph Cooper, Louise Pattison, and the Online Distributed Proofreading Team (http://www.pgdp.net) Note: Project Gutenberg also has an HTML version of this file which includes the original illustrations. See 35024-h.htm or 35024-h.zip: (https://www.gutenberg.org/cache/epub/35024/pg35024-images.html) or (https://www.gutenberg.org/files/35024/35024-h.zip) Transcriber's note: This is Paper 44 from the _Smithsonian Institution United States National Museum Bulletin 240_, comprising Papers 34-44, which will also be available as a complete e-book. The front material, introduction and relevant index entries from the _Bulletin_ are included in each single-paper e-book. Mathematical notation used in this e-text: 1. Greek letters are represented by the name of the letter in square brackets; _e.g._, [pi]. 2. Subscripts are denoted by underscore followed by the subscript in curly braces; _e.g._, T_{n}. Superscripts are denoted by a caret followed by the superscript in curly braces; _e.g._, T^{n}. To avoid possible confusion, subscripted variables which are raised to a power are enclosed in brackets, thus (T_{1})^{2} represents 'T one squared'. 3. Square root is denoted by [sqrt]. 4. To improve readability, italic markup (underscores enclosing text) has been omitted from letters used in mathematical formulae, and some equations have been set 'out of line'. Please see the end of the book for a list of corrections. Smithsonian Institution United States National Museum Bulletin 240 [Illustration] Smithsonian Press Museum of History and Technology Contributions from the Museum of History and Technology _Papers 34-44_ _On Science and Technology_ Smithsonian Institution · Washington, D.C. 1966 * * * * * _Publications of the United States National Museum_ The scholarly and scientific publications of the United States National Museum include two series, _Proceedings of the United States National Museum_ and _United States National Museum Bulletin_. In these series, the Museum publishes original articles and monographs dealing with the collections and work of its constituent museums--The Museum of Natural History and the Museum of History and Technology--setting forth newly acquired facts in the fields of anthropology, biology, history, geology, and technology. Copies of each publication are distributed to libraries, to cultural and scientific organizations, and to specialists and others interested in the different subjects.