Extract start/end times across multiple dates with multiple times

[edcfour]

I have a spreadsheet with a large number of timestamped entries. Column B contains the Date and C contains the Time. I would like to be able to find the first and/or last event for each unique date. I've tried several approaches, but I'm stumped.

 

[ranman256]

youd sort the sheet on Date
then I run a macro to scan down the list,
get the date, continue until you reach the last record of that 1 day,
post the elapsed time.
repeat