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Scientific Item Detail

Item #


1901 Locke Adder Calculator 1st Model



Price $


This adder was made in 1901 by the C. E. Locke Mfg. Co. in Kensett, Iowa, U.S.A.  Note that this is one of their first models with only red & yellow colored sliding bar keys and NO green painted sliders (most likely a prototype or early model).  All other 1901 and 1905 models had multi-colored sliding keys of Red, Yellow & Green.  The left side says The Locke Adder, Patented Dec 24, 1901.  The next models were stamped 1901 & 1905 and more common.  The 1901 model was 1st and truly a collectible with red felt base (Note – Felt is removed to reveal owners writing on bottom that might add value and if desired to preserve).  The old 2 piece felt pieces can be glued on bottom if desired.   Machine is pictured and described in the book “Antique Office Machines” by Thomas Russo.  Invented and patented by C. E. Locke of Wisconsin in December 1901 with Patent Number 689,680.  It was a finger sliding bar type adder with color-coding to readily tell dollars and cents.  The Russo book states “Availability is Scarce and value of each is over $ 800.00”.   It measures 10 3/4" long, 4" wide and about 1/2" thick.  There are 9 rows of moveable numbers, and on the left side there are marking points that go from 1 cent to 1 million dollars, on the right side the markings delineate units up 100 million.  Machine is made of stamped tin painted black.  Although some paint loss, Instrument is in good operational and display condition.  This rare treasure will highlight any collection of old calculators.

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