DaVinci's Inventions

            Jack: Since the lifting of weights is one ofthe most common problems of the
            engineer and mechanic, Leonardo gave it much study, designing devices using the
            principle ofthe pulley, the screw, and, as here, the ratchet in a form that anticipates
            the modern automobile jack.

            File Cutter: Though there is no record that such a machine was built, it is workable
            in principle. It involves two ideas significant for the future: first, the use of a threaded
            shaft to control automatically the movement of the file blank so that it may be evenly
            scored by the trip-hammer, and second, the use of a falling weight as a source of
            power. The latter is a clockwork mechanism here applied to an industrial use.
            Therefore the machine represents a step toward automation, an idea that recurs in
            Leonardo's notebooks, but was not to be realized for centuries.

            Spring-Driven Car: It is doubtful that any such vehicle was ever constructed.
            Though springs had been known since ancient times, their use to supply power first
            appeared in clocks and watches made after Leonardo's time. He recognized their
            potential usefulness in such theoretical designs as this, and in a drawing for a flying
            machine in which springs were intended to provide an aid to manpower.

            Automatic Turnspit: Such devices were known in various automatic and
            semiautomatic forms since ancient times. In this version Leonardo shows his
            knowledge of the principle of convection, since the spit turns through the action of
            the rising hot air on the fan set in the chimney flue. In another turnspit he applied the
            clockwork mechanism of the falling weight to turn the spit, using a fan vaned with
            goose feathers as a governor.

            Roller Bearings: Leonardo carried out many experiments with friction, including a
            transmission system. He found that roller bearings, as here applied to the revolving
            axle of a wagon, were excellent "friction removers," a function they continue to fulfill
            in many different situations.

            Gear Study: Drawings of gear systems recur throughout Leonardo's notebooks,
            often, as here, theoretical rather than applicable to a specific device. Similar systems
            to this later appeared in clocks and clock-like mechanisms, and variations of them
            are in common use today.

           Wire-Testing Device: Like modern scientists and engineers, Leonardo wanted as
            precise information as possible about the properties and capacities of materials so
            that they could be used more effectively and economically. By weighing the basket
            after the breaking of the wire had automatically shut off the flow of sand he could
            determine the tensile strength of the wire.

            Printing Press: Gutenberg is generally credited with the invention of the printing
            press nearly a half century earlier, in about 1448, but Leonardo seems to have been
            the first to attempt a basic improvement by making it potentially possible for one
            man to operate it instead of several. A turn of the screw draws both type bed and
            paper under the platen and supplies the pressure to print, while a reverse turn
            releases the bed. The first practical applications of such improvements had to await
            the early 17th century.

            Variable Speed Drive: Another theoretical gear system that anticipates a number
            of modern applications. By meshing the three cogged wheels of different diameters
            to the same lantern wheel, three different speeds of rotation result, a principle used
            in the transmission of the modern automobile.

            Hydraulic Screw: By encasing a waterwheel, the water turbine was developed in
            the early 19th century. Leondardo's horizontal impluse wheel, driven by the weight
            of falling water, and his hydraulic screw were important steps in this direction. Like
            the turbine, the hydraulic screw works with greater efficiency and a smaller water
            supply than the older overshot or undershot type waterwheels.

            Spindle-Shaped Hull: Intensive study of the action of water and the shapes of fish
            led Leonardo to design hulls of greater stability and less friction &127;than the
            round-bottomed vessels then generally in use, and somewhat similar to certain
            sections of mod em racing hulls. Each side of the model illustrates a different design,
            each developed from an experi mental and functional point of view similar to that of
            modern engineering and marine architecture.

            Double-Hulled Ship: If the outer hull of such a vessel were damaged, either by
            enemy action in time of war, or by reefs or floating wreckage, the inner hull, still
            intact, would keep the ship afloat. In more recent times both double hulls and the
            division of the interior of the vessel into separate compartments by watertight
            bulkheads have carried Leonardo's ideas toward still greater safety at sea.

            Two Level Bridge: In reserving the upper level for pedestrians and the lower for
            vehicles, Leonardo used the same idea for traffic control that appears in his plans
            for an ideal city in which entire streets were thus restricted. The truss is similar to a
            type used in bridges since the early 19th century.

            Rotating Bridge: Designed to connect an island stronghold with the mainland, this
            bridge could be swung across a stream or moat and back again by means of
            windlasses. Swing bridges have proven to be practical only in relatively short spans.

            Flying Machine: This early design called for a wooden framework and two
            movable wings to be activated by the aviator who lies prone in the framework, and
            works the wings by pulleys connected with stirrups moved with his feet, aided by
            the windlass worked by his hands and arms. In later designs, often with more than a
            single pair of wings, Leonardo has the operator standing upright.

            Helicopter: Leonardo was fascinated with the form of the spiral which often
            appears in nature, and is involved in the principle of the screw. His helicopter takes
            the form of an aerial screw, following the example of a device earlier brought to
            Europe from the Far East in the form of a children's toy. Of his design for the
            helicopter he wrote, "If this instrument made with a screw be well made - that is to
            say, made of linen of which the pores are stopped up with starch and be turned
            swiftly, the said screw will make its spiral in the air and it will rise high."

            Parachute: "If a man have a tent made of linen of which the apertures have all been
            stopped up, and it be twelve braccia across and twelve in depth," Leonardo wrote,
            "he will be able to throw himself down from any great height without suffering any
            injury."

            Scaling Ladder: To reach the top of the wall of an enemy fortress, Leonardo
            designed this scaling ladder in a form similar to that employed today in fire-fighting
            apparatus. It is elevated and lowered by means of the crank and the large toothed
            gear.

            Triple-Tier Machine Gun: There are eleven barrels in each tier. While one is
            fired, another tier is loaded, and the third cools. This weapon, like others Leonardo
            designed, shows him constantly attempting to achieve greater fire power.

            Military Tank: Leonardo designed this ancestral version of the tank to carry
            heavy fire power and be driven by men working the enclosed wheels with cranks.
            Its turtle-like cover was intended to deflect enemy fire. "These," he wrote, "take    the place of the elephants. One may tilt with them. One may hold bellows in them to
            spread terror among the horses of the enemy, and one may put carabineers them to
            break up every company."

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