The machines of Doctor Roth (1800-1885)

Bibliographical elements

*English version by Eric Schurmann, November 2008*

I) David-Didier Roth, Hungarian refugee, Homeopathic doctor

Source: Brody, Judith.- An émigré physician : Dr David (Didier) Roth, homeopath, art collector, and inventor of calculating machines.- Journal of Medical Biography, 2000; 8; pages 215-219.

David (Didier) Roth was born in 1800 at Cassovia*1 in Hungary under the Hapsburg monarchy. At this time, anti-semitism was particularly strong  but the Roth family seemed to benefit from special permissions. (Jews had to stay outside the town). His father died when he was 10. His mother, who had a private income, stayed in town and worked at a kosher restaurant. The young Roth left to study in Vienna. The medical school in Vienna was highly conservative and homeopathic medicine, commended by Samuel Hahnemann, was really not the flavour of the day. It was not authorized until nearly 1829. It was probably at that period that David Roth stood up for this new medical approach. In 1830, a cholera epidemic struck Austria. There was panic in the towns. The Jews were accused of poisoning the wells. In the circumstances, one can understand why Roth, a young medical graduate, would decide to leave Austria for a somewhat gentler country. He practised homeopathic medicine for a rich Parisian clientele for 30 years. During the 1840s, he was consulting physician to the Austrian Embassy in Paris.
His editorial production was not negligible.! In 1832, he published his "Health Instructions against Cholera Morbus", the fruit of his "Hungarian experience". He said he had cared for a large number of patients there.  Between 1836 and 1840, he published "Homeopathic Clinic", an enormous compendium in 9 volumes recording nearly 5,000 clinical observations. His "History of irresistible musculature or normal chorea" earned him a medal from the Académie Nationale de Médecine in 1850. His talents for translation (English/French/German) made him an unavoidable publiciser of homeopathic thinking in Europe.


II) Dr Roth inventor of calculating machines

Source : Multiple !

What could have possessed our doctor to leave the homeopathic circle to invent calculating machines? Since 1822, things were pretty calm on the mechanical calculating front. It is true that the economic and social circumstances were not very propitious !

The 1840s, boosted by the Exposition Nationale of 1844, mark the beginning of the great adventure.! Between 1840 and 1844, Roth registered 6 patents - totalling 72 pages - quite something!


Date of registration

Date of issue


Source patent

21 May 1840

28 September 1840

1st addition

18 June 1841

11 October 1841

2nd addition

27 October 1841

7 May 1842

3rd addition

24 November 1842

31 December 1842

4th addition

15 march 1843

17 april 1843

5th addition

18 march 1844

5 june 1844

At the Exposition Nationale in 1844, he presented several calculating machines as well as gas meters. He was awarded a bronze medal for his inventions.

Extract from "Report of the Exposition Nationale of 1844"
"Dr Roth presented arithmetic machines which he had invented for the jury to examine; some intended only for the two first rules, the others, more complete, working multiplication and division as well; he also presented meters for steam machines and other similar devices. None of these machines is new in its intended purpose; but Dr Roth has solved these various problems by simple means worthy of interest. The jury awarded Dr Roth a bronze medal."

Another inventor, whom we all know, also presented several calculating machines: it was Thomas de Colmar. He only received a medal of encouragement.
Did the two men know each other?

Little anecdote.
In March 1843, one of the biggest homeopathic pharmacies was set up in Paris at 15 rue du Helder (Pharmacie Catellan). Dr Roth must have been there from time to time. Thomas de Colmar lived right next door at No 13. Amusing! No?

What is certain is that Roth knew of Thomas' work because he mentions it in a descriptive memo registered on 18 June 1841 as a prelude to his second patent (Patent of addition and improvements).

His small adders had a certain commercial success. In 1843, a patent was registered by a certain David-Isaac Wertheimber (cf the Wertheimber mystery), his commercial agent. One also finds models adapted to the Russian, German and Italian markets. The Conservatoire des Arts et Metiers even has a Japanese prototype.!

They were reliable and very cheap.

Théodore Olivier, Professor of descriptive geometry at the Conservatoire des Arts et Metiers made a highly complimentary report on them to the Société d'Encouragement pour l'industrie nationale, on the 12th July 1843 (Cf BSEIN).
After examination by L Lalanne, engineer in the railways section, the Public Works Ministry ordered 12 of them on the 29 June 1844 (9 of the ten digit model and 3 of the eight digit model).

To this day, we do not know the total number of adders built by Roth and Wertheimber. Unlike Thomas de Colmar's arithmometers, there are very few in public and private collections. There are not more than about thirty but that figure is provisional.
The Musée des Arts et Métiers in Paris has the biggest number (about twenty). Practically all of them come from the old collection of Edouard Lucas who donated them to the museum in 1888. (Had Lucas acquired them from Roth shortly before he died in 1885 or did he buy them in the Roth sale at Drouot in 1887 ?)

It's interesting to note that all the Roth adders are in decimal mode, even those whose writing is in Japanese. On the other hand, those bearing the Wertheimber mark are exclusively machines adapted to foreign markets (England, Germany, Italy, etc.).
It would be fitting to look into the role of Wertheimber in this affair: simple commercial agent ? Mechanical engineer as was Payen for Thomas ? I'm very much afraid that there's still a great deal to discover !

As regards his multiplying machine, only two prototypes are known (CNAM). It is to be feared that Roth never built other examples of it. And yet an article in The Times dated 13 October 1841 raised some hope. The article indicated that Prince Albert ordered two during a demonstration at the Polytechnic Institute in London. *3

Mail direct to the archivist at Buckingham Palace! But reply…negative!
To be continued…. because the royal cupboards have not all been opened yet!!!

Note that Roth invented two other multipliers. One, with small rulers, is more a calculating device than a machine to be exact because it doesn't have a carry mechanism. The other is a very interesting, permanently engaged multiplier, simpler than his circular machine. A part of the mechanism is presereved in the racks of the CNAM. It is not known if our inventor built a whole model. (For more information see the section "Models").

Finally, we know very little about Roth's relationship with his calculating machines because one must admit that the majority of the documents available are concentrated on only 4 years. Four short years during which he registered his patents and worked on the construction of his instruments.
And then, nothing. He was absent from the Exposition Universelle of 1849 while other inventors presented calculating machines (cf Thomas de Colmar, Maurel & Jayet). No Roth at the Exhibition of 1851 in London nor in Paris in 1855. It would seem that our man gave up mechanics.

Up to the 1860s, he continued practicing homeopathic medicine for a rich clientele in Paris.


III) Dr Roth, art collector

Source: Brody, Judith.- An émigré physician : Dr David (Didier) Roth, homeopath, art collector, and inventor of calculating machines.- Journal of Medical Biography, 2000; 8; pages 215-219.

Passionate about art, he managed to build up a very beautiful collection of old engravings, notably by Dürer, of which the Bibliothèque Nationale now holds the treasures. (cf Roth sale? 1888?)
His sure and well-trained eye made him an inescapable art consultant for the Rothschild family. (Don't forget that, during the 1840s, Roth was private physician to the Austrian Ambassador in Paris who was none other than the Baron Rothschild.)
As his sight deteriorated with age, he amused himself by surprising his friends. One of them only had to read the inscription on the bottom of an engraving for our enthusiast to give a complete description of it.
When he became completely blind, he sold part of his collection to the Rothschild family. A collection now held by the Louvre.
Roth had no children. He is buried in the Montmartre cemetery with his wife Nathalie Sassary and his stepson.

*1 Now in Slovakia
*2 In fact, he hoped to win the Civrieux prize from the Academy but couldn't finish it in time.
*3 As well as two adders.


*English version by Eric Schurmann, November 2008*
Valéry Monnier