I don’t think the mail car was a home-built job when comparing it to the two box-car converted cabooses. The side door slides on the inside as you’d expect on a baggage/express car or drover’s caboose. Also, the presence of a roof over the end platforms where the other two cars lack one tells me that is probably the original configuration of the car, and the railroad bought it 2nd-hand. The Tuscarora Valley RR had an almost identical RPO car, so i’d bet it was built by one of the common narrow gauge carbuilders. (Jackson & Sharp, Billmeyer & Smalls, etc.) The hoses would in all likelihood be original equipment to the car, simply unused by the CR&N, and tucked away.
Automatic train brakes on narrow gauge equipment weren’t common in the early 1880s, but not unheard of either–particularly on passenger and express equipment. (The Ohio River & Western had automatic brakes on its passenger equipment in 1880.) It’s possible this car could have been originally equipped with either Westinghouse air brakes or Eames vacuum brakes. That would account for one hose. The second, I think, is likely steam heat. Mail contracts stipulated that the mail car be heated in the winter, and these cars were often run immediately behind the locomotive so access to steam wouldn’t be an issue (provided the loco was so equipped to deliver it).
The CR&N likely didn’t have steam heat fittings on any of their locos, thus found it easier to just install a stove in the mail car to provide heat. So, having neither automatic brakes nor steam heat, the two connections would be of no use. It’s likely the car came equipped with some kind of hanger device for the hoses to keep them out of harm’s way when not in use, thus making it easy for the CR&N crews to simply leave them in place.
That’s my theory, and I’m stickin’ to it. (Until more evidence pops up, at least.)
Later,
K