According to a former SP steam-era fireman who
actually fired GS-class locomotives, these
locomotives were, indeed, good steamers, and
rode quite well. And they did know exactly
how fast they were going, so they would not,
for instance, go too fast around curves. And,
yes, milepost markers were pretty darned accurate,
and were not always just placed on lineside telephone
poles, but were also placed on special lineside posts
when needed because there was not a telephone pole
exactly a mile fron the last mile marker.

Agentatascadero ---
Thanks SO much for the account of riding the Argonaut
\at past the century mark! Wow..... You are VERY
fortunate to have experienced that! Those were the days.....