Not to be confused with the one-string- or phono-fiddle? This is a bit on the rare side these days, but it had a plain or sometimes fretted fingerboard, a single string, a soundbox like that on an acoustic gramophone, a horn; and little else^*. You play it as described: vertical, on your knee or leg. I've seen a Web page with pictures, but I forget where. I'm told there was a four-string "violin" version - like a kind of Dobro violin, almost - designed for the old mechanical recording phonographs, to concentrate all the sound into the recording horn.

Steve

^*But it didn't bend in the middle, whatever Robert Service might have thought ...