GDG- Time Line for Gettysburg Day Two

[James Cameron]

<< Standard Time was established in the United States and Canada on 18 
November
1883, in order to standardize railroad schedules. Before that communities
used local sun time, and the military, when it was concerned about exact
time, would have used the Washington Naval Observatory time. However, no one
really cared about exact time. That is a 20th Century Phenomena. The one
exception to that was ships trying to locate their longitude.  >>

The only real way to pin down an exact time would be with reference to an 
astronomical observation, such as sunrise, sunset (in the case of 
Gettysburg, behind the mountains), or moonrise or moonset.  The locally 
observed time could then be converted to standard times for the same event. 
Or local apparant noon could be adjusted to modern standard time, based on 
how far west Gettysburg is in the time zone.

Even that, however, would be of only limited utility, in that time 
references in reports and accounts vary so widely, for the same events, due 
to the factors already noted.  There's generally no way, for example to say 
exactly how long after sunrise, or before sunset, a certain brigade 
advanced, or a specific battery opened fire.

Jim Cameron