B65-274 GRAVITY INCLINOMETER. Rufus Porter. Very rare example of the inclinometer invented around 1847 by Porter, noted inventor, painter and founder of Scientific American. All known examples have an engraving, presumably by Porter, showing two masons using the inclinometer to build a brick wall; in this example the engraving is clear and complete; one of the nicest examples we've seen, with "R. Porter" and "Patent Applied For" printed in red although no patent has ever been located. In a 9-1/2" square frame, glass looks original. Destined to be the highlight of any advanced collection of inclinometers. Fine 3000-6000