Wednesday Search Challenge (Jan 25, 2012): What was Art Thorpe's job?

Forgive me if I ask you another question about historic San Francisco.  But I ran across this intriguing man in the mists of San Francisco history, and I can't pass up the chance to teach you another great search trick in the process.  


Meet Arthur A. Thorpe.  He lived in San Francisco at the turn of the century... the one before the last one.  To make things easier for you, I'll even tell you he lived in SF in 1899.  

We know he enjoyed several hobbies (I'll let you figure out one of them), had a pretty nice handlebar mustache, centrally parted hair, and had an occupation that was once common on the Bay, but is VERY rare these days.


Can you figure out what Art's job was during 1899?  


And, for extra credit, can you estimate how many other people in San Francisco had that job as well? 


When you post your answer, please include the URL where you found the answer, the search path you used to figure it out, and how long it took you to get to the secret! 


I'm guessing that this is difficulty level 3.  (This is on my informal Russellian scale where the max difficulty is 5.  Level 1 is a simple 1-query search that takes less than 30 seconds, while a 5 is a full day's worth of work with many queries along the way.)  


Search on!