In his essay "The Mysterious Arthur Watson" in our 2001 edition of The Annals of Conjuring, Bob gave the whole story.
In 1999, Gordon Bruce called Bob's attention to two 1909 articles on early magic history by one Arthur Watson in The Reliquary and Illustrated Archaeologist.
Bob and Edwin Dawes quickly realized that two important conjuring historians (Sidney Clarke and Kurt Volkmann) had used Watson as a source, but no one had any idea who Arthur Watson was.
Thus began Bob's (as usual, somewhat tongue-in-cheek) quest to find out more about this mysterious author who had never received credit for uncovering some of the major keystones of early magic history.
At this year's LA Conference on Magic History, Bob told me how pleased he was to give his lecture and finally get Arthur Watson out of his system.