Jacopo Chimenti (c 1551–1640), an artist from Empoli, made two sketches of a young man holding a compass and a plumb line. When these were seen, mounted next to one another, by Alexander Crum Brown in 1859, he combined them by overconvergence and described the stereoscopic depth he saw. Brown's informal observation was conveyed to David Brewster, who suggested that the drawings were produced for a stereoscope, possibly made by Giovanni Battista della Porta. There followed a bitter debate about the supposed stereoscopic effects that could be seen when the pictures combined. Brewster's claims were finally dispelled when precise measurements were made of the drawings: some parts were stereoscopic and others were pseudoscopic. Brewster's attempts to wrest the invention of the stereoscope from Wheatstone were unsuccessful.