Snuffy, thanks for the thread ref. You're quite right: it's London "docks," not "tops," which doesn't make much sense.

The shanty makes it pretty clear that a "bullgine" was a fire engine and not (at least in this case) a locomotive.

I suspect that the New York fire-engine stuff was inspired by the 1848 smash-hit show "A Glance at New York," which introduced the character "Big Mose," a NYC "Bowery Boy" who was also, prominently, a volunteer fireman. More information here, including references to Mose's supposed adventures at sea:

http://ahistoryofnewyork.com/2009/02/big-mose-must-of-dropped-it.html