During the Civil War and beyond, the Post Office Department evaluated various processes for producing postage stamps from which cancellation marks couldn't be chemically removed and the stamps used again. Starting in August 1867, postage stamps began to bear the physical marks of the POD's chosen solution: the Grill--stamp paper embossed by steel points, said to cause canceling ink to more readily soak into the paper. But grilling was just one of dozens of alternate approaches patented by inventors for manufacturing un-reusable stamps. Their ideas reflect a wide range of ingenuity, from stamps printed with fugitive inks (soluble in cancel-removing chemicals) to those embedded with an explosive "bang cap" and canceled with the blow of a hammer. Remarkably, thousands of examples of these experimental stamps survived and are in collector's hands. Inventions of Prevention explores this field in encyclopedic fashion, but goes a significant step further than previous research on the subject... The History of Reuse Despite over 130 years of philatelic authorship on these experimental stamps, key questions about them remain unaddressed. For example, grilling increased the cost of stamp manufacture by 66%. Was reuse ever so rampant as to warrant the added expense? When was reuse most prevalent, if at all? Why didn't the Post Office simply demand the use of more indelible canceling inks by postal clerks instead of considering more complicated solutions? What prompted inventors to address the issue? And so on. Chapters 1 & 2 chronicle the actual extent of postage stamp reuse from 1860-1870, identify when it first became a tangible problem, and explore inventors' efforts to thwart it. The conclusions drawn from this study may come as a surprise to most philatelists who have studied this subject previously. Revenue Stamp Reuse The Bureau of Internal Revenue also struggled with the issue of stamp reuse, and Chapter 3 analyzes that state of affairs from 1862-1875. It chronicles the trials and tribulations of Butler & Carpenter in their dealings with NY inventor Henry Loewenberg, the tension resulting from his encroachment on their printing contract, and their forced testing of his patented but unproven methods. The chapter also includes a brief look at the reuse of taxpaid stamps instigated by the Whiskey Ring of the 1870s. Chapter 4 explores opportunities for new research in the field--of which there are many--and includes the author's analysis of the well-known exploding revenue essays, one of the more outlandish (some might say "crackpot") methods for preventing stamps from being used a second time. The Patent Catalog The bulk of the book consists of the annotated Patent Catalog, a compendium of 129 patents and diagrams related to preventing stamp reuse. It is profusely illustrated with associated essays, stamps, and rarely seen patent models--printed in full color for the first time in any philatelic literature offering. It also includes commentary and analysis of many prevention-of-reuse patents and essays, and calls into question some of the long-standing associations between them. Inventions of Prevention is intended both as a primer for collectors new to the field and as a reference source for the advanced student, bringing together a massive amount of information on the subject in one volume.