I hate when I continue to misinformation on locks. I have looked further into Kromer and found he has 2 US lock patents from the early 1870's. This does help support the fact he was here but his locks were nothing like later Kromer locks, the non- changeable (Pork Pie LOL) Protector and Novum or the Convar, which is the modern changeable lock starting this post. I haven't thoroughly read the patents but they used push keys much like the William Hall designed Herring Grasshopper keys. So Chatwoods lock may be the first key lock to use that particular method of geared levers mated to gear wheels containing the gates. Doug