what's the extra pipe for in my toilet?

the toilet is at least 50 years old. the tank and bowl are separate pieces, connected by a 1.5" pipe threaded at both ends.
connected to the underside of this pipe is 1/4" tubing that runs down and into the wall. i think that this might hook up to an equally mysterious 1/2" pipe that runs down next to the 4" cast iron dvw and presumably connects up with it under the slab.

without a picture, anyone know what this tubing is?

i'm guessing that it's some sort of overflow protection? but wouldn't i lose water through this path every time i flush? and 1/4" doesn't seem big enough anyway to stop an overflow.

I bet two jelly-filled donuts that it is a unapproved trap primer for one of your floor drains in your basement.

hmm, not likely.
there's only 1 floor drain in the basement, and it's probably 20 feet to the north. the basement floor drain is below the kitchen sink and in the laundry area so there's other water closer.
it sure seems like it would be for overflow, but i don't know why they would have brought it all the way down (via the mystery 1/2") through the basement and into the slab. it's (obviously) right next to the toilet drain. and since there doesn't appear to be any sort of valve, why doesn't some of my flush water get lost this way? (maybe it does and it's not considered a big deal in the days of 3 gpf.)

another odd thing is that the upstairs toilet appears to be of the same vintage and has the same 1.5" elbow joining the tank and the bowl w/ the same fittings, but doesn't have a 1/4" tube coming out of the elbow. maybe the upstairs toilet is somewhat more modern.

i'm going to be having a plumber come by at some point, and i'll try to remember to revisit this and post the answer.

Instead of paying a plumber I would disconnect the tube and run water through it and see where it ends up. In my area in the urban parts they did this to keep the smell down in traps because they would dry up in boiler rooms all the time due to high temperatures in the room, causing the traps to evaporate due to lack of use.

well, rugged, two jelly-filleds coming your way. yellow or red?

i had a plumber in today to scope out the project and he said that it was a trap primer. not sure why they didn't choose a closer source back in 1927. Maybe they also used a toilet.

he also said that when i replumb i'll need to reconnect this to something.

tp

They used a toilet, and something similar is also done these days, because it was a conventient source of frequent water use. There are also lavatory tailpiece trap primers that work the same way.

Both flavas, it's been a long wait for those donuts