About 10 years ago I became interested in the Guillaume Balance Wheel (GBW). From a number of experts, qualified watchmakers I was asking a simple question. How does a watch collector visually determine or recognize a GBW? I got a number of “mumbo-jumbo” answers, none of which made sense. I decided to do my own scientific research. I spent hours in Libraries and countless hours at watchmakers peering through large stocks of 1000s of loose balance wheels. I also contacted the BHI to see if they had anything on the subject. The BHI were gracious enough to send me a (facsimile) folio of a lengthy correspondence in French between Dr. Guillaume and Mr. Robert Gardner the famed British Chronometer maker. The correspondence revolves around a commercial venture where Dr. Guillaume, through his manufacturing agents Messrs. Ferrier & Vaucher were to supply Mr. Gardner with his Guillaume Balance Wheel granting him exclusivity for Great Britain and Ireland. One of the conditions stipulated in the contract by Dr. Guillaume was that any marine Chronometer produced by Mr. Gardner should have the name "Guillaume Balance" either on the dial, a visible part of the chronometer or in the very least had to appear on Mr. Gardner's final invoice to his client. Though a contract was signed between the two gentlemen, the deal fell through due to Mr. Gardner's (alleged) ill health. Mr. Gardner did however purchase a single sample (probably for evaluation) of the Guillaume Marine Balance Wheel at a cost of Two Pounds Sterling in 1901. The correspondence ends with Dr. Guillaume threatening legal action for breach of contract. Another interesting fact revealed in that correspondence is according to Dr. Guillaume that Mr. Nardin (of Ulysee Nardin) were using his GBW almost exclusively in their pocket watches. Through my research and the correspondence above, it became clear that the GBW was a PATENTED geometric design with very specific layouts of the timing screws. In pocket watches the GBW was in use between 1899 and approx. 1925. The GBW was slowly phased out in favor of a balance wheel made of brass and Invar and controlled by a balance spring made of Elinvar. Now here is a curved ball that should be of interest to collectors of high grade pocket watches between 1899 and 1925: The term "Guillaume Balance Wheel" is only to be associated with a laminated (brass on the outside and Anibal on the inside), cut, compensating balance wheel controlled by a balance spring made of plain STEEL and known to be affected by temperature changes and MAGNETISM. Using the name Invar or Elinvar associated with the GBW is erroneous. If the inside of the balance wheel is made of Invar and/or controlled by an Elinvar balance spring it is no longer a GBW. While doing my research I was keeping notes on my computer. Through those notes I was able to compile a full 12 page (easy to understand) technical paper on my findings with diagrams and pictures. Included in the paper were complete details on how to visually recognize the GBW. Ironically I contacted the Editor’s of NAWCC’s Bulletin who were very keen on publishing it. After 2 or 3 years of email correspondence with the Editors an approximate date was set for publication. For reasons unknown, since then my emails have gone unanswered and the paper was never published.