When I first get a new blook or at the time of cataloging it, I look closely for any patent information and search for an original patent document. If the object is American, it couldn't be simpler, as these can be searched and downloaded using Google Patents. Many objects may have some version of "Patent Applied For" printed on them, but I'm fairly sure that while this was a deterrent to the theft of a design, most of these objects were never patented. Having said that, I haven't done a thorough patent search for objects in this category, so I could be wrong.
In the case of secret book flask, Secrets of the American Cup, or, The Cause of the Controversy (Vol. 1, by Richmond B. Stoehr), the patent information was subtly blind-stamped on the interior of the top opening flap. It isn't easy to read, but shows the name if the inventor (Charles A. Brackett) and the U.S. patent date (Jan. 13, 1903). There is a detailed photograph of the stamp below.
There are all kinds of great reasons to search for patents. What's so wonderful about them, is that you always find out something interesting about the object. Some examples of this are:
- Some objects, as purchased, are incomplete and the patent will show you how they were originally envisioned by the inventor.
- You can see and read about how the object is constructed and what materials were used.
- You find out more about the inventor, such as their gender, where they were from, what company they worked for or owned, etc.
- You find out if there were revisions to the original design and what version of the object you have.
- Sometimes you accidentally find a patent for an object by browsing Google Patents and this tells you that something you thought was unique, is not.
- Some objects, such as in the case of Secrets of the American Cup, are shown in the patent as a having a slightly different function.
There are a number of blooks (as well as patented bookbinding structures) in my collection that I have found patents for. This is only one example. In this case, the patent shows that the inventor chose to illustrate this box as a candy box in the patent, although he does mention that it could be used for a bottle or flask in the text.