משנה אויף ישעיהו 40:15

A gutter spout cannot cause title through possession [so that the spout may still be moved] but title through possession may be claimed to its place [so that the place must be left for its present purpose]. A gutter can give title through possession. An Egyptian ladder cannot give title through possession but a Tyrian ladder can. An Egyptian window cannot give title through possession but a Tyrian window can. What is an Egyptian window? Any through which a man’s head may not enter. Rabbi Judah says: “If it has a frame, even though a man’s head cannot enter through it, it can give title through possession.” A projection, if it extends a handbreadth or more can give title through possession, and the other [into whose premises it projects] can protest against it. But if it is less than a handbreadth it cannot give title through possession and the other cannot protest against it.