Nice! Haven't seen a brass one in a long long time. They got plastic ones at the 99 cent store so you scored! Oh, if you use it don't leave it out overnight!
Open a lawn sprinkler museum as a tax right off. I found this one at a site the former residence of my area once tossed all their old junk away. Form what find around there, it appears folks were dumping stuff there from the late 19th century and looks as if it was put to a stop around the 1970s as it was most likely deemed an illegal dump by then?. You can have this old sprinkler as a donation to your Sprinkler History Museum.