The language of physical objects was picked up from obscurity by the invention of motors and the demands of commerce and business. Commencing in the late 1800’s, _desk calculating machines_ (see No. 19) were constructed to meet mass calculation requirements. They would add, subtract, multiply, and divide specific numbers with great accuracy and speed. But until recently they still were adjuncts to the other languages, for they provided figures one at a time for insertion in the spaces on the ledger pages or calculation sheets where figures were called for. Beginning in the 1920’s, a remarkable change has taken place. Instead of performing single operations, machines have been developed to perform chains of operations with many kinds of information. One of these machines is the _dial telephone_: it can select one of 7 million telephones by successive sorting according to the letters and digits of a telephone number. Another of these machines is a _fire-control instrument_, a mechanism for controlling the firing of a gun. For example, in a modern anti-aircraft gun the mechanism will observe an enemy plane flying at several hundred miles an hour, convert the observations into gun-aiming directions, and determine the aiming directions fast enough to shoot down the plane. _Punch-card machinery_, machines handling information expressed as punched holes in cards, enable the fulfillment of social security legislation, the production of the census, and countless operations of banks, insurance companies, department stores, and factories. And, finally, in 1942 the first _mechanical brain_ was finished at Massachusetts Institute of Technology. THE CRUCIAL DEVICES FOR MECHANICAL BRAINS Let us consider the two modern physical devices for handling information which make mechanical brains possible. These are _relays_ and _electronic tubes_ (Nos. 21 and 22). The last three kinds of equipment listed in the table (_magnetic surfaces_, No. 23; _delay lines_, No. 24; and _electrostatic storage tubes_, No. 25) were not included in any mechanical brains functioning by the middle of 1948. The discussion of them is therefore put off to Chapter 10, where we talk about the future design of mechanical brains. [Illustration: FIG. 1. Relay]