Calling at the agreed time

If I agree to call a friend at 9 tomorrow morning, how will I know what time to call?  That's easy: look at the clock and call when it's time.  But it takes a bit of time to go to the phone.  It takes a further bit to dial.  It takes a further further bit for the call to go through.  So, allow for the use of a little lead time in which to place the call.  How much lead time?

This sort of worry-warting is exactly what I read about in Edward Boring's "History of Experimental Psychology".  Evidently these minute differences in estimating, reading and recording times showed themselves to be important in astronomy.  When we are dealing with astronomical events, it can be important to record events very accurately.  But my colleagues on other continents will see events at different times.  Besides, their timepieces may not be set as accurately as mine.  Or, they may be more accurate.

In the age of broadcast media, where there was no system of choice, the broadcast of an important event was available at a given time and not otherwise.  Many people wanted to tune in at the agreed -on time and not miss any of the broadcast.  We are in a transition period when you may be able to catch a recording of the program if you have the right equipment.