I'd use the hour, minute, and second to convert each time to seconds past midnight. Then, since it promises that the delta t is the same between any consecutive elements, you can just compare the seconds from element 2 back to element 1. For example
secsToday = 3600*hours(1) + 60 * minutes(1) + seconds(1);
Do for (2) and then subtract to get the delta t in seconds.
If hours is not a 24 hour clock, then you'll have to take that into account. For example t1 = 12:59:30 p.m. and t2 = 1:00:30 p.m. Perhaps you can just scan the data until you find times where t2's hours are definitely more than t1's hours. Or else just add 12 to t2's hours.
