Abstract: A music box comprising two opposed metal combs with tuned steel teeth respectively disposed at two opposite sides relative to a pinned barrel, a driving mechanism to rotate said pinned barrel, and an adjusting device controlled to move either metal comb into the operative position, wherein rotating said adjusting device in one direction causes the tuned steel teeth of one metal comb to be struck by the pins on the outer wall of said pinned barrel in producing a certain tune or tunes; rotating said adjusting device in an opposite direction causes the tuned steel teeth of the other metal comb to be struck by the pins on the inner wall of said pinned barrel in producing a different tune or tunes.

Abstract: An isometric ellipse scale for drawing ellipse of different size, comprising a body, a plurality of isometric ellipse molding plates that set one inside another, two fastening slides, and a casing for keeping said parts. The body and the isometric ellipse molding plates have each two pairs of parallel rails at two opposite ends and respectively longitudinally aligned so that the fastening slide can be respectively fastened therein to selectively secure the isometric ellipse molding plates to the body for drawing ellipse. The casing has an elliptical, raised portion at the center of the inner bottom thereof and made in size according to the elliptical center hole of the smallest one of the isometric ellipse molding plates for holding the isometric ellipse molding plates and the body in position.