Stanley Fuller Model 1 calculator/slide rule with mahogany box, stand, and instruction booklet. This calculator is a cylindrical slide rule with a spiral scale 500 inches long (12.6 metres) which gives accuracy to four or five significant figures. The serial number is 6401 over 31 which means it was manufactured in 1931.
D Scale length: 12566 mm. Significant digits: 4.7 to 5.