The Thacher calculating instrument was patented in 1881. It was cylindrical and could slide back and forth, giving it the power of several individual slide rules. It could do multiplication and division, and calculate interest, roots and powers of numbers to about five significant figures. It was also accurate to within about .01%, incredible accuracy for that time.
SEE THE LAST EDITION OF GONE BUT NOT FORGOTTEN--MAIL ORDER RECORD CLUBS!--AT https://everythingcroton.blogspot.com/2018/03/gone-but-not-forgottenmail-order-record.html
HARD TO BELIEVE THERE WERE EVER MAIL ORDER RECORD CLUBS!
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