Bob, sorry to have to correct you after your excellent original introduction to windpower. But--the old and popular Jacobs generators did not have a gear box. Jacobs did make a few of one model with a gear drive way back in the early days of the company (1930s??), but it was not popular, and although I have seen many dozens if not hundreds of old Jacobs generators, I have seen only a few parts of one of the old gear drive ones.
The current Jacobs machine, and the similar ones built since the 1970s, do have a gear box, but they are quite different from the old original direct drive Jacobs generators. By the way, my 1940s vintage machine has been working well since we first installed it in 1979, although we did replace the blades and governor in 1999. Here's a little info on both the old and the new:
Jacobs Wind Generator Systems
Jim