Recueil des Brevets d'Invention
The basics on these tomes
These are the primary source of patent listings and categorization of patents filed and documented by the Belgian state, that is, patents filed in Belgium. This nation is under-represented within espacenet. Classification information too was found by way of the volumes Recueil (Spécial) Des Brevets d’Invention. From the 1800s to shortly after 1900 these volumes were known as the "Recueil Spécial des Brevets d'Invention", then the word “spécial” reappeared on the cover of the 1917-18 volume but not the title page.
Use of this resource is straightforward though time-consuming. It is only available on paper, so far as we know, not having been digitized, to the best of our knowledge.
Facilities at which these tomes may be accessed
The volumes of Recueil des Brevets d'Invention and the original patents are housed at the AGR 2 - Cuvelier facility in Brussels. The Recueil (Spécial) des Brevets d'Invention volumes are also to be found at the STIC library of the USPTO. In general terms, these facilities both offer the bulk of these volumes. However, at STIC, these are “rare books”, which affects reliability of access and is also reflected in the extreme deterioration of some of the tomes in question. As an example, Recueil Spécial des Brevets d'Invention 1913, January-August volume, which is immense, is in very fragile condition. We got only the BE K material of January 1913, which leaves us with difficult judgement calls, in terms of even estimating the Belgian aero-patents filed that year. At the AGR 2 - Cuvelier facility, on the other hand, self-service is outright promoted, with none of our team noting any extreme wear and tear.
At least in the later years, each year has two volumes, the index material for the two volumes being included at the end of the second volume. As with the French Bulletin Officiel de la propriété industrielle & commerciale, the volumes are sectioned into months, and the months are sectioned according to invention categories.
Approaches to the data
One searches the indexes, by patent title, inventor name, or field, such as "Aviation", such an example naturally often overlapping with patent title, or titles. Finding particular patents sought, perhaps following references made within other patents, Belgian or otherwise, is not difficult. Finding new material is also rather simple. Cross-tasking can be a matter leading to some complications if time is of the essence.
For the Belgian material pertinent to the years we are studying, this is the most efficient manner in which to find the patent number, and thereby conceivably to request access to the original.
One peculiarity of the indexes in these volumes has to do with word choice. An index search of the word "aéroplane", for instance, will yield broad results, all of which are pertinent, only roughly half of which will have the word actually in the title and-or in the descriptive summary. All will be pertinent to aircraft. A few will go beyond BE K, usually the classification most pertinent to us, and into classifications BE J or BE L. This happens even though a look at a word list associated with the BE K classification may have led to the word choice. In these latter cases the results are always pertinent to the airplane, the inventions being relevant engine parts, structural elements and so forth. The word upon which the search is based is the analogue equivalent of a keyword, reflecting the thinking behind the patent's classification, and in some rare cases leading the researcher beyond the otherwise likely "best" classification.
As seen on the “Recueil spécial des brevets d’invention Tome 55 1907 pertinent index material” featured on the right, key terminology varies over time, notably as the airplane gains prevalence. In this sample, while looking for “aéroplane”, which is directly handy in later volumes, we find, alphabetically, “Aérostat - ballon”, then, separately, “Aérostat dirigeable - en général”. This latter is subdivided into “plus léger que l’air, aérostat (ballon)”, “aérostat dirigeable”, and “plus lourd que l’air”. This is all to say, that “aéroplane” is not treated as an index term, though “heavier-than-air”, quite likely leading to patents along the lines of the airplane, is represented some 55 times. This has to do with the key status of the airplane, which we late-moderns may take for granted, not being assumed earlier in the developmental trajectory on which we are gathering data.