Pick the last reading and time of that reading

HI
I thought I knew Excel, but I am getting in areas I don't know very well. I have a table of gauged heights and the gauges or readings are done between 4 tanks. Each hour a tank is gauged until it is full and than we starting filling the next tank. I need to come up with two items or figures. I need to know what time the last reading was taking and what tank that reading came from. I guess I need to create a table or and array, but like I wrote, I just do not know how or what excel functions to use. Your help will be appreciated.
Oh, I have attach a sample sheet.
Thanks again
Ted

Questions

Are the tanks filled in sequence Tank 1 then Tank 2 then Tank 3 then Tank 4 then Tank 1 ...??

The number sequences look messed up. As the tanks fill over time, the heights should increase(not decrease like tank 3 7-9 am).

Number are filled in ONLY while the tanks are being filled?

Most of the time, the tanks are filled in sequence but there could be times when we mixed things up. Sometimes, we only have 3 tanks to work with too. When you see the numbers decrease, that is show the tank was unload and is ready to be filled again.
Thanks
Ted

Dgagnon, thanks for the first part or the time of day. It is working. I can not get your next equation to work as it is giving me a (0) for an answer.
Thanks

Dgagnon, I posted your 2nd equation into the my sample work sheet, and it works. Thanks, but I have a question. I posted it to my spreadsheet, changed E37 and B:F to reflect the new worksheet, and it does not work. Do I have to change anything else? Like 2,0 or 3,0?
Thanks
Ted

Thanks, I got it to work!!!!!
Ted

HI DGagon
I have a strange issue with the vlookup equation. The current answer is 1, but when I test that with an If/than statement, 1 does not equal 1. Do you know what is happening here?
Thanks
Ted