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The Thinking Machine

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Dean Boelter, left, watches operation of Mechanical Differential Analyzer.

Between 1947 and 1950, the College of Engineering received four of the first "thinking" machines, promising post-war wonders devised to "take the drudgery out of mathematics." The four "analyzer" machines are the mechanical differential, electrical differential, network, and thermal analyzers. The amazing new high-speed computing machines (which newspapers have mechanical brains or electronic brains) will tackle problems never solved before. They can predict accurately how a rocket motor will work even before it is built, and will make child's play out of the complicated statistics of the census or income tax. They can estimate the impact on the nose wheel of an aircraft landing with a force too dangerous to be tried in actual testing, and can predict the speed at which a gas turbine will vibrate according to its design. These machines, along with another called the Automatically-sequenced Digital Computing Machine, which will be part of UCLA's Institute for Numerical Analysis, serve to establish UCLA as the West Coast "brain center" of the "thinking machine age."

The first machine received, the General Electric mechanical differential analyzer, consists of an interconnected system of shafts, motors and gears, and electromechanical elements. The machine employs these mechanical elements, whirring, buzzing, and clicking away, to perform addition, subtraction, multiplication, and division, and the electromechanical elements for more complex functions. One of the most important elements of the differential analyzer is a Polaroid photoelectric system of unique design which GE developed. Fourteen of the highly sensitive devices are installed on the machine, thus permitting the accurate, speedy solutions of differential equations requiring as many as fourteen simultaneous integrations.

In appearance, the GE analyzer resembles a long maze of shafts and gears with input and output tables extending to one side. When the machine is in use, the variables in the differential equations being solved are represented by the rotation of shafts in the machine. These are connected with mechanical pens, which, in turn plot an accurate curve in accordance with the quantities worked out by the continuous movement of the shafts. Interpreted correctly, this curve gives a graphic solution of the problem.

In December of 1977, the last working model of a mechanical differential analyzer in the world is donated by UCLA to the Smithsonian Institution for its pioneering computing display. The differential analyzer introduced much of Southern California industry to automatic computing, but became obsolete beginning in 1960 as it was replaced by computing machines with electronic circuits and vacuum tubes. From 1960 on, it was used mainly as a display piece, clanking away occasionally for student and public demonstrations.