This key-set, non-printing stepped drum calculating machine has a metal case painted black. Each of the nine columns of keys has nine black plastic keys. Between each row of keys, rods that are black ...
Scientific American is part of Springer Nature, which owns or has commercial relations with thousands of scientific publications (many of them can be found at www ...
TimesMachine is an exclusive benefit for home delivery and digital subscribers. About the Archive This is a digitized version of an article from The Times’s print archive, before the start of online ...
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