Hi, Meta.  If you are referring to John Bergstrom of San Francisco,
California, USA, he was in business from the late 1800s until the
1930s, dates uncertain.  I had the pleasure of dismantling one of his
organs in St. Peter's Catholic Church in San Francisco about 1990.
It had been poorly cared for in its last years, but one could see that
it had been a fine instrument.  More than that, I cannot add.

Regards,
Bob Loesch, in beautiful Lake County, California, USA
http://home.jps.net/~rrloesch/index.htm