I found this today while detecting at a site where 3 1890s-1920s houses were demolished. I found some old relics and I came across this glass tube. It has a slider inside and I have no idea as to what it is. One side of the slider is flat with a crosshatch pattern on it. The other side of the slider has a peg that fits into the hole at the stubby end of the tube
Any ideas? Is it a valve of some kind?
Any ideas? Is it a valve of some kind?