日晷炮（英语：sundial cannon）是由日晷、火炮和凸透镜组成，用以在正午报时的装置。当日晷炮的日晷对准正南北方向时，它能够以悬挂在火炮斜上方的凸透镜会聚日光，在正午点燃火炮引信。英文中它也称作正午炮（noon cannon、noonday cannon）或子午线炮（meridian cannon）。日晷炮的尺寸依用途有所不同，可大可小：作为家用物件的日晷炮可以用来为午餐报时，而大型的日晷炮可见于公园的正午报时。
SUNDIAL GUN Made in 1788, this "gun" uses the heat of the sun's rays, rather than any type of lock, to fire. The purpose of these so-called sundial guns is to announce the arrival of noon. The purpose of these so-called sundial guns is to announce the arrival of noon.
A dry wadding is rammed home in the muzzle of the gun and when the dial is mounted upon the parallel for which it is cut, the gun would discharge at twelve o'clock noon fired by the concentrated rays of the sun as it crossed the line.
As the sun works around to noon, the solar rays are focused on the fuse, and with the blast, liberated woman knows that dinner is served.