Historical zone changes

[Lblumbbs at aol.com]

In December 1941 I understand the time in Hawaii when it is on the hour in 
the Eastern Standard time zone was 30 minutes past the hour.  Today ther 
minutes are the same.  Can you tell me what the time zone difference between 
the Eastern Standard time zone and the time zone covering Hawaii was in 1941? 
 Can you tell when (year and month) any changes to this time difference 
changed.