Hi,
I think all of Tesla's inventions were great, just the usage of those in the improper hands (like scalar technology), gives it a bad reputation. This applies basically to any invention man has created.
I think
Peter Davey's ultrasonic boiler would have also had been a great invention, if massively produced. However we all know where the boundaries of all "too good inventions are". Just look up T. H. Mooray's story.
This would give alchemy a totally different boost. I think it is possible, therefore, a tuning fork is also a good invention. Hey, if it worked for carving those giant rock formations around the world (Easter Island, The Pyramids, Coral Castle from Edward Leedskalnin,...)...