Late 19th - 20th century, each on a circular marble base having a cannon, a magnifying glass in brass frame, a dial, and a gnomon. Such instruments can be calibrated so that the sun ignites a primed cannon at a specified time.

the larger dial 4-1/2 x 7-1/2 x 8-1/4 in

Private Collection of an Antiquarian, Charlotte, North Carolina

The larger piece with wear to dial and no touch hole on the cannon, suggesting heat alone causes a discharge; the small dial appears unused, yet theoretically should work.