Someone on a Swiss watchmaking forum found a pocket watch form around 1870 made by James Nardin. There is very little information available on this watchmaker, and some confusion on the details. We did some research and she contacted the Museum in Le Locle. Here is what we found:
The museum in Le Locle answered her query with the following information:
There is some biographical information on James Nardin in Biographical dictionaries of Swiss Watchmakers and of Le Locle Watchmakers, and in "La mesure du temps en mer et les horlogers suisses" by Estelle Fallet.
There are, actually, two James Nardin:
1. James Nardin (1814-1885), AKA Nardin-Perret (Perret was his mother's maiden name), the father, a direct cousin of Ulysse. The Locle museum has a death notice dated May 22, 1885 (Ref.: Nar-6.25 A-400725). He was the founder of the watchmaking firm bearing his name.
Au XIX siècle, l'histoire de la chronométrie de marine Neuchâteloise conserve le nom de James Nardin. Cousin germain d'Ulysse Nardin, chronométrier au Locle et fondateur de la fabrique qui porte son nom, James inscrit son nom dans les registres de dépôts de l'Observatoire de Neuchâtel en 1873. Son chronomètre de marine porte le n° 75. Il ne nous est pas possible de certifier si sa production de chronomètres de marine fut continue ou éparse...
2. James Nardin (1836-1880), the son. He also was involved in the production of marine chronometers. He is most likely the maker of the marine chronometer (No 75) acquired by the Observatoire de Neuchâtel in 1873.
Marine chronometers from that era were mostly originating from the James Nardin manufacture, rather than Ulysse Nardin's.
On August 17, 1869 he US Patent Office delivered Letters patent no. 93,735 to James Nardin, of Locle, Switzerland, assignor to V.T. Magnin, Guédin, and Company, of New York, for "Improvement in stem-winding watches".
If you have any more information, I would really like to share it!