Yahagi, thanks very much for the information you have posted. With regard to the dating, I have a number of clocks in my data that have service dates, presentation dates, DRGM Patents, etc., from 1883 to 1899 that clearly show Schnekenburger's batch numbering system and signing of his logo had to begin no later than the beginning of 1883 and in my opinion actually before that in second half 1882. It "may" be possible that the clocks without a RSM Rose logo and no batch number were made by Amman, however they are completely identical to those of the same design made with the logo and no batch number. Once the batch numbering system started I have found no evidence whatever that clocks were made that did not have this numbering AND the RSM Rose logo, first the large format design and starting in 1893 the small format design.
Also it is physically impossible that the dating system and signing started in 1890 or later. Serial number 79310 is the first of several clocks in my data stamped with DRGM 113027 for a bit-bam strike control, which was granted 8 March 1899 and obviously used from that date until its expiry in 1902. Had all the signed movements been made starting 1890 (lowest serial number documented to date 46_16) that would mean that more than 8,800 clocks per year would have had to be made from 1890 to first quarter 1899. The actual production rates confirmed by confirmed date examples are in the order of 4,000 to 5000 clocks per year from 1883 to early 1899.
My data also show that only about 210 clocks were made before the introduction of the batch numbering system. This estimate is based on there being five different design movements with two having 2 variants as I mentioned earlier, and none of these has a serial number higher than 28 at this writing and after collecting data for more than 15 years.
| MOVEMENT DESIGN/VARIANT | LOWEST SERIAL NUMBER | HIGHEST SERIAL NUMBER |
| Time Only Spring Drive No Logo | Lowest: 6 | Highest: 17 |
| Time Only Spring Drive RSM | Lowest: 4 | Highest: 24 |
| Time Only Weight Drive RSM | Lowest: 5 | Highest: 25 |
| Time/Countwheel Strike Sprg No Logo | Lowest: 12 | Highest: 26 |
| Time/Countwheel Strike Spring RSM | Lowest: 3 | Highest: 26 |
| Time/Rack Strike Spring Drive RSM | Lowest: 14 | Highest: 22 |
| Time/Rack Strike Weight Drive RSM | Lowest: 5 | Highest: 28 |
My opinion is that Schnekenburger started production of each movement design with a separate set of serial numbers, all beginning with the number 1, and soon found that he could not manage either quality control or inventory with several clocks all with the same serial number but of different types. He developed his batch numbering system before these first clocks were completed and introduced it very quickly to ensure he could manage his business. On point easily concluded from these examples being such a small number, is that this very small quantity would not in any way have supported Schekenburger's business for any significant length of time. There is no question his production was in the low thousands per year early on, also that there were at least 79,310 clocks made by early 1899 and at least 153,230 made by the time the RSM Rose logo was no longer used from October 1913.
I have not included the full striking torsion pendulum 400-Day Kohler-Bauer Patent wall clocks produced initially by Schnekenburger (1894-1895), as these had a completely separate set of serial numbers. Schnekenburger's production of these stopped by end 1895 and was moved to the factory of Carl Bauer of Furth. where sales started in January 1896 and continued to about 1900.
Finally, with regard to the clock you have posted that has the date 13/12/1893 written (wonderful find!!!) it is possible this was a sale date as you have supposed. I would more likely think it was a service date put there by a repair person, as this clock per my date would have been made at least a year earlier. However, it is also possible this clock was made much earlier than it was sold, not at all unusual in those days.
One thing I have not yet confirmed with certainty is the actual date when Amman sold the business to Schnekenburger, other than sometime in 1882. Do you have any documentary evidence of when this occurred? My data are easily adjustable to account for the actual date.
