Not only could they could be isolated, but asserted that they could be tuned harmoniously with each other by altering the shape of the bell itself. He claimed that it is not possible for a bell to be properly tuned upon casting, but instead that adjustments needed to be made to tune it. His assertion was put to the test in 1644. The city of Zutphen commissioned the famous bellfounding duo Pieter and François Hemony to cast a new carillon for its Wijnhuis tower. The city appointed as their consultant. He convinced the Hemony brothers to tune their carillon bells according to his research before finishing the job, rather than waiting for a negative review from the city. To achieve this, François cast the carillon bells slightly too thick so that they could be shaved down while tuning. Where other bellfounders haphazardly shaved the inside of a bell in an attempt to fix its tune, François placed them on a lathe rotated by five or six men to guarantee symmetry. He then shaved down the insides with a chisel to tune the five principal tones. Hemony carillons outfitted with "pure" tuned bells quickly became the standard and were coveted across Europe for decades. 's acquaintance with the intellectuals of the time along with his longstanding relationship with bellfounders helps explain how he was able to influence the Hemony brothers.