David Cassel completed United States Pattern Postage Currency Coins, A Survey of U. S. Pattern Postage Currency 10-Cent Coins of l863 and the Related Issues Dated 1868 and l869.  He starts out with a reproduction of a series of articles from COIN WORLD by Douglas Winters as a place to begin studying these patterns.  He reports on the literature, examining what others have done, and then analyzes a vast number of past sales, undoubtedly more than anyone else has done, as regards these specific patterns.  He goes a step further and tells us the ANA definition of numismatics starts out, " The science, study or collecting of coins…"  Certainly, no more scientific study of any series of coins has been conducted than Cassel's survey of these pattern coins.  It certainly deserves the words, "scientific" and "study."  He accepts previous authors' techniques of visual examination and weighing the coins as being valid, but up to a point.  He has gone to the trouble, and expense, of having many of these coins tested using scanning electron microscopy with energy-dispersive x-ray analysis.  All pattern postage currency coins in his personnel collection have been so tested as well as many which reside in other collections.  Cassel states that some areas reported by others may seem disproved and others unproved.  "One just needs to obtain the correct evidence to prove or disprove a stated fact," and his book does this in many cases.  Concordance tables, based on his research, and including the numbers from the Judd and Pollock pattern books are furnished.  His system allows for interspersing new discoveries and changes in information and is available to all users of the inter-net through "our pattern club" at uspatterns.com. While he has limited his study to the pattern postage currency coins, he invites students of the hobby to examine other series as well.  Several tables summarize much of the information described in the text, and 25 well chosen, high quality plates illustrate the book.  A glossary is provided, and he has included a "Bibliography of Numismatic Auction Catalogues of Postage "Currency Coins in Chronological Order, many with Provenance."  Only 110 copies of the book, all numbered, were published, and as of this writing, only a handful remain.  Cassel has indicated revisions may be published sometime in the future.  David Cassel's book, 225 pp; hardcover, $145; postpaid is  (SOLD OUT, However A.N.A. Members in good standing may borrow a copy from the A.N.A. Library.)