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great condition. clean. Box is missing latch.
EARLY MODEL:2 PATENT MODEL EARLIER THAN 3 PATENT (1901) MODEL.ON THE BACK OF THE HEAD IT DOES NOT HAVE THE 1901 PATENT DATE.JUST SAME 2 1896 PATENTS HAT ARE ON THE INSIDE OF CASE.SERIAL NUMBER IS 1294
Edward Jones Willis (1866–1941), a steam and electrical engineer from Richmond, Va., patented a cross-shaped planimeter in 1894 and had a modified version of the patent reissued in 1896. This is the first patent mentioned on the instrument. Willis\'s 1895 patent for a planimeter with a frame similar to the frame on this example and a horsepower attachment is not mentioned on the instrument; see MA.323704. Alpheus C. Lippincott of New York City received the second patent mentioned on this instrument, for a different form of cross-shaped planimeter.
James L. Robertson & Sons manufactured steam engine indicators. Since planimeters were used to measure the area under curves drawn by these indicators, it was common for firms that made indicators to also produce planimeters. Indeed, Robertson sold both the Improved Willis Planimeter and the Lippincott Planimeter, so it is probable that the company mentioned Lippincott\'s patent on this planimeter by mistake.
In 1901 Willis patented the form of wheel mount found on this instrument, which Robertson manufactured and sold as the Improved Willis Planimeter. Its price was $18.00 in 1905. The company apparently ceased operations in the 1910s.
