* Translation by Serge Roube

There is very little information existing about the Mechanical Engineers that worked alongside Thomas de Colmar to build and improve his Arithmometer.  What we know is that they had skills and creativity! And Thomas knew how to motivate them!

The CNAM owns a weighing scale made by Devrine from 1809 with an accuracy of 1/20 of a milligram.  He was without doubt a manufacturer of precision instruments as well as being the first manufacturer of the Arithmometer!  Unfortunately, we do not know anything else about him!

T1822

It seems that no machine was built between 1822 and 1844.  Thomas might have been too busy with managing his insurance companies (Le Soleil and L'Aigle) of which he was Managing Director.
The Arithmometer resurfaces in 1844 at the “Exposition Nationale de Paris”.  Several models seem to have been displayed there but unfortunately none have been found.  In 1848 a machine built by Piolaine comes out of his machine shop!  The patent of 1849 provides clarity of this:

“ ...Mr. Thomas is not a mechanical engineer; He had to rely on workmen to whom he had to explain his ideas, and after two or three years of work, they had to be remake everything:  the parts were not properly made, the motion was not smooth.

Eventually Mr. Thomas found a young man, Mr. Piolaine, son of a Neuilly clock maker, who was put in charge of completing the workshop of Mr. Thomas, and manufacturing in front of him, a machine with a new mechanism. Shortly thereafter, the young man lost interest in the work and left for England.
In the meantime, Mr. Thomas had another Arithmometer built (a grand), but the workman improperly built some pieces:  the machine did not work.

Still keeping at it, he brought Mr. Piolaine back from England at his own expense, and first had him fix the previous Arithmometer;  He reworked all the pieces, remade quite a few and finished it in July of 1848.  This machine works flawlessly.

Immediately after, they started a new machine with a simpler design.  The young man fell sick and died in 1848 without finishing the machine he had started before leaving for England or the new one he was working on after finishing the Grand.

Many workers busily finished the two machines started before Mr. Piolaine’s death and some less important ones that were subsequently manufactured, all under the watchful eye of Mr. Thomas; they showcase some new and important improvements.”
Patent number 8282 from April 25th 1849.

Arithmomètre T1848, built by Piolaine

In the printed media, Piolaine is mentioned as well:

“ ...and it is not without great difficulties that this inventor (Thomas) has been able to reach this outstanding result;  as he is not a mechanical engineer, he had to explain his ideas to his workers, his ideas were often not quite complete, and his workers couldn't help him or suggest corrections and often couldn't even understand his ideas.

Only one, a young man called Piolaine, son of a clock maker from Neuilly, has proven to be intelligent enough and has started a machine based on a completely new mechanism; He was about to finish it, when he died unexpectedly in 1848.  Fortunately the machine was far enough along in construction that someone else was able to finish it and we saw it working a few days ago” L'illustration No 347 from October 20th 1848.

Arithmomètre of 1848 shown in "L’illustration"

Once again we have very little data on the Company Hoart & Cie and on Mr. Hoart himself !

Here is what we know:

In Conclusion :

Without doubt, Hoart was involved in the construction of the Arithmometer! We can deduce that Hoart was the manufacturer of Thomas Arithmometers from 1850 to 187.. ??? At this time it is hard to tell anything else.

To be continued ....

Payen is without doubt the most well-known manufacturer of Thomas Arithmometers.  We don't know if he knew him personally.  It is even possible that he joined the workshops after he died in 1870.
Thomas de Bojano takes over his father's business and continues the manufacturing of Arithmometers.  Incidentally this is the time when the Arithmometer really starts  to take off.  The literature is plentiful, which is also a clue !
The manufacturer is already Payen.  Incidentally, there might have been more!
Payen quickly becomes the legal representative of Thomas de Bojano for the manufacturing of Arithmometers.  It is mentioned in the patent of 1880.
I would venture a guess that around 1878 Payen takes control of the manufacturing, because he is mentioned a great deal from that year on!
What was his relationship with Hoart ?  We don't know.
When Thomas de Bojano died, in 1881, the manufacturing operation continues, possibly under the leadership of a grandson of Thomas.
Until around 1887, the machines are stamped Thomas de Colmar, then Payen !!!

P1	P2	P3

The first PAYEN models (P1) are identical to the Thomas models that he manufactured anyway !!
And then he comes out with the new models P2 and P3 until he dies in 1900-1905.  His widow Léontine takes over and even filed for a new patent in 1907 !

P4

We know that in 1915, Léontine sells her business to Alphonse Darras, who has a store in Paris at 116 Boulevard St Germain.  This is a known fact ! He used to work for the  "Maison Deschiens" , which had been a manufacturer of meters since 1870.

Darras would have continued the manufacturing of Arithmometers well into the 1920s, but so far, we have only found the Arithmometers that were listed in the Darras inventory made in March of 1915.  Did he only liquidate the inventory that he had acquired ?

Alphonse Darras