Not radio, because this is 1840, but a good attempt with regular materials.
If I was sticking a library on the moon, I would put it on the poles. Unless there is a huge meteorite impact, those will stay in much the same place. If you were looking for something that was put somewhere on the Moon for you to find, this would narrow it down to one of two places.
The next thing you could do is to have some sort of passive reflector, like a set of wires that would show up on round-mapping radar…
Or stick it next to the one the dinosaurs left.
Dammit. Bang goes my working day - I am going to be thinking about this now.
