Electrotype to Empirical rule.

Electrostatic speaker. A loud­speaker utilising the principle of a membrane vibrating in a strong electric field.
Element. (Chern.) That form of mat­ter which cannot be decomposed by any means known to scienec. One of a limited number of dis­tinct varieties of matter which, sin­gly or in combination, compose every material substance.
Elementary. Treating of the first prin­ciples of anything. Of or pertain­ing to an element or elements.
Elements of a storage battery. (Elec.) The positive and negative metal plates of a storage battery in which chemical changes take place dur­ing charge and discharge.
Elevation. (Draw.) A geometrical pro­jection on a vertical plane, as a view in mechanical drawing.
Elevator. (Aero.) A movable auxil­iary airfoil, the function of which is to impress a pitching moment
Elevator angle. (AelV.) The angular displacement of the elevator from its neutral position. It is positive when the trailing edge of the elevator is below its neutral position.
Elevator rope. (Engin.) Wire rope composed of hemp core around which are located 6 strands of 19 wires each.
Eliminating. Act of getting rid of; casting out. Setting aside as un­important or inapplicable.
Elixir of life. (Chem.) A mythical substance sought by the alche­mists and believed by them to be capable of prol0nging life.
Elk hide. (Leathfr.) A heavy, soft leather suitable for moccasins and shoes.
Ell. (Arch.) A wing or addition to a building (orming an angle with the main structure.
Ellipse. (Geom.) A plane curve, such that the sum of the distances from any point. of the curve to two fixed points is a constant. (Math.) Area = long diameter x short di­ameter x 0.7854.
Ellipsoid. (Geom.) A solid, every (Shopwk.) Gears, in which the plane section of which is an el- shaft is not in the center. of an Elipse or a circle. most any shape-oval. heart­
Elliptical arch. (Arch.) An arch, el- shaped, etc. Printing presses usu­liptical in form being described ally have good examples of these. from three centers.
Elliptical stylus. A stylus shaped so that its width across the groove is Elliptical or eccentric gears on the aircraft.the elevator is usually hinged to the stabilizer

Elm. (Wood) A coarse, open-grained wood much given to warping; little used in engineering or woodwork­ing.
Elongation. (Mech. Engin.) Malle­able iron and steel, when subjected to tensile stress, elocgates up to the breaking strain with a conse­quent reduction of area. The amount of elongation and reduc­tion of area it undergoes is consid­ered a test of its quality. (Plast.) The increase in length of a stressed material.
Em. (Print.) The square of a type body. The cost of setting reading matter is generally based on a price per thousand ems.
EmbeUish. To ornament or decorate. To beautify by adding ornamental features.
Em~lazon. To adorn with figures of heraldry.
Emblem. (Fum.) A symbolic orna­ment often used as a carved deco­ration.
Embossed. (Shopwk.) Decorated or richly ornamented with raised fig­ures. (Papermkg.) Paper decorated with raised or depressed design.
Embossed split-grain cowhide. (Leather.) Less expensive but simi­lar in appearance and used for the same purposes as grained cowhide.
Embossing. (Art Met. dnd Ceram.) The process of decorating with raised ornamentation. (Print.) Print­ing by the use of dies so as to leave the design in relief.

Embossing hammer. (Art Met.) Used for working on the inside surface of hollow objects. .
Embossing plate. (Print.) ~ plate cut or etched below its surface into which the paper is forced for the purpose of raising the image of the printed surface.
Emergency brake. (Auto.) A hand­operated brake commonly known as a parking brake. Rarely used in actual driving except when the car is stopped on a grade. Its prin­cipal use is to prevent motion of a car when parked.
Emergency flotation gear. (Aero.) A device attached to a landplane to provide buoyancy in case of an emergency landing on the water.
Emergency switch. (Elec.)A switch connected ahead of the power company's meter for the purpose of disconnecting current from all ~ parts of a building in case of an emergency of fire.
Emery. A species of corunaum com­posed of oxide of alumina, iron, silica, and a small portion of lime. It is used as an abrasive.
Emery cloth. Powdered emery glued on thin cloth, used for removing file marks 'and for polishing me­tallic surfaces.
Emery wheel. (Mech.) A wheel made of emery. It is revolved at a high speed and is used for grinding.
Empennage. The tail surfaces of an airplane.
Empirical rule. (Engin.) Any rule or equation which is not deducted (rom purely mathematical or physi­cat" considerations, but which is