Surprisingly, this compilation...

https://bluejacket.com/usn_avi_lta.html

indicates that the the earliest classes of Navy dirigibles (A, B, C) were filled with hydrogen. It wasn't until C-7 that helium was used.

I suspect the smaller of the two tubes was used to spill the water ballast so the ship could rise. The other tube might be a gas vent for descending. Maybe that tube is a fill tube. In either case, why the strange angle?