Old Time Water Vat Tank Car Tops

Been searching the net for plans/pics of prototype or models of those (old time) water cars with the vertical (vat) tanks. All the models I’ve seen have vats that are open on top. I could be wrong, but find it hard to believe that in prototype operation, to prevent water from sloshing everywhere, they wouldn’t have had a top and perhaps some type of filler hatch. Does anyone out there have info or insight on this minor detail. Thinking too, there would have been some type of spigot or valve on the lower side to drain out the water. Does that make sense? Thanx, Tanked - in Irvine, CA

P.S. My apologies if this topic has been previously covered.

Cowcatcherrider,

From picture I have it shows 1x4 board across top with five of the boards has a leather type hinge across them, seven of boards are fixed with a outlet with canvas bag to allow water fill up.

Hope this help. Edward