Mystery car- extra tender or "canteen"

I was looking through the Canada Southern website (great website) and I came across this 4-6-0. It looks like an extra tender but I wanted to some more info. from the more experienced people out there in the world.

Here is the link to the best picture of the mystery car:

http://www.canadasouthern.com/caso/imag ... 1290-3.jpg

Thanks.

Scott W.

Scott,

It's a "canteen", extra tender (cistern only) used to extend distance between water stops or if intermediate branch line stand pipes had been removed from service.

Thank you Shlustig.