My original plan was to create a database of Luxembourg patents up to 15 February 1945 , the grant date of the first Luxembourg patent incorporated into the ESPACENET database set up by the European Patent Office.
I was, of course, aware of the Luxembourg patent law which entered into force on 30 June 1880 since it was the law that was still in force when I started my professional career in patents in 1973. I also knew that the Patent Register started with patent n° 1 in 1880 and that in the 1970s it had reached patent n° 80.000. Because patents privileges are limited in time, one rarely looks further back than 20 years.
When I started the present project, I did not know that a patent law had already been introduced in the territory of Luxembourg as early as 1791 under the French Regime, and that this law continued to be in force until 25 January 1817 when the Dutch Regime under Guillaume I introduced a new patent law for the Royaume des Pays-Bas, including the Grand-Duchy of Luxembourg. 
It would appear that at least two Luxembourg residents obtained a patent of invention under the French Law of 1791 as co-inventors  before the Dutch Law of 1817 came into force.
The patents granted to Luxembourg residents under the Law of 1817 are documented in the National Archives. This law required that Luxembourg residents filed their patent applications in Luxembourg-city and submitted the applications to an examination procedure before grant.
A total of 13 patent applications were thus filed between 1817 and 1829 and they were recorded under numbers 1 to 13 in the Register of patent applications. Only two of these passed the examination stage and were granted.
In 1830, when the Belgian provinces separated from the Royaume des Pays-Bas, the area of patent protection of the Royaume broke into three separate territories. From then, patents in Luxembourg could only be granted for the Grand Duchy of Luxembourg and this, of course, had an impact on the Luxembourg Register. The old Register was kept, but the numbering system was discontinued and no new numbering system was introduced.
Of the 322 patent applications filed between 1830 and 1880, only 177 patents were granted. As the patent applications did not receive official identification numerals I decided to allocate sequential numbers to them according to their date of entry into the Register.
However, the Register was not kept with great care so that a number of applications were not recorded ; I included them in my listing in the appropriate time sequence by allocating them numbers with a "letter" suffix (e.g. n° 13a, 19a ...).
When the 1880 Law came into force on 30 June 1880, it overlapped with the 1817 Law, as a number of patents under this new law were still pending examination. However, the 1880 Law allowed for patents filed under the 1817 Law to be converted to patent applications under the new legal system and many applicants took this option.
Under the 1880 Law a new numbering system was introduced, starting with N° 1 on 10 July 1880.
During my searches I came across inventors which were Luxembourg nationals or resided in Luxembourg and had obtained patents in France. These inventions are documented under the listing entitled French Law of 1844.
In the Chapter Search guide I have made an attempt to provide an overview of the various « actors » involved in the Luxembourg patent system up to 1880.
 Patent No 27,693
 The only publication on the subject-matter of patents in Luxembourg is that of André Elvinger (Aspect du droit des brevets, Conférence faite devant le Jeune Barreau à Luxembourg le 9 mars 1956).
 WILLCOX Richard/ROUYERE Jacques-André (1812). From 1791 to 1804 an average of 19 patents per year were granted in France and from 1804 to 1815 an average of 71 patents per year.
 The existence of these applications is evidenced by the administrative files kept in the National Archives.