I first became aware of the Castaing machine when I attended the 1984 Coinage of the Americas Conference at the ANS. George Ewing submitted his paper on "Origins of Edge Lettering on Early American Copper Coinage," This includes material that may expand your knowledge of the subject.

French Engineer Jean Castaing ranks in the top twenty most important people who developed minting technology. I ranked these for my Encyclopedia of Coin and Medal Technology. Castaing came in at number 19. His invention of the edge-treating or edge-marking machine was pivotal in the development of coining in the late 17th century.

But it may not have been his original idea. There is some validity that it may have been developed earlier by Pierre Blondeau (ca1620-1664) a Frenchman working in the London Mint. Blondeau was highly secretive and did not want anyone to know of his development (perhaps that is why he is not given credit for this invention).

However, the story is that the French Ambassador gained the information about the device from the Royal Mint in London and passed it on to Castaing at the Paris Mint. There Castaing build a working model in 1685 and this was publicized. (It would be nice to know the first coin to be so edge lettered or treated with Castaing's invention -- if a London Mint product had such treatment.)

We don't know details of Castaing's life. I would be delighted if some researcher could uncover the dates of his birth and death if nothing else.

In addition to the references given last week, Castaing is also listed in Forrer, volume 1, page 359.

Five additional sources of information on Jean Castaing can be found in ANS search and World Catalog. I hope this helps out a little.