A lead at last! While speaking with a couple people in the Palaeozoic Museum, they mentioned that the person most likely to know what happened to the time machine would be the owner of the library itself. Logical, and I kick myself for not thinking of it before. Ms. Knight and I then went to the library itself, and while the owner was not there, we did find the address for her place of business. Going there, we also failed to find her, but luckily I was able to leave her a note in the building's mailbox.
Later, I recieved her worrying reply. Apparently the time machine had never been recovered, and there was rumors that Obolensky had used it at least once... This confirms that Obolensky stole the machine and may still have it in his posession. However, before I take any sort of action, I'll need to be sure. While asking the doctor directly may be foolhardy, I believe that one of his henchmen, Mr. Merrick specifically, may be more open to questions.