High resistance to Horse

to Hogging

than in low relief.
High resistance. (Elec.) Rust, corro­sion, or any other influence which interferes with or blocks the full flow of electrical current under normal voltage.
High speed. (Auto.) Relates to posi­tion of speed-change gears for nor­mal open-road driving which gives a one-to-one ratio from crankshaft to drive shaft.
High-speed steel.. Steel containing tungsten or.molybdenum, which has been added to increase its efficiency for cutting tools~ Such tools can be operated at much higher speeds withoutinjury than can be ordinary carbon-steel tools.
.High spots. (Mach.) (I) Spots to be taken down by scraping or grind­ing in order to secure an absolutely plane surface. (2) Area of a plane extending above a true plane.
High tension. (Elec.) A high voltage or e.m.f. (SEE HIGH POTENTIAL.) High-test fuel. (Auto.) Gasoline of 75 octane rating or better.
High voltage. (Auto. Elec.) (I) Refers to the voltage in auto circuit which rises higher than the normal 6 volts, due to faulty generator cutout (relay) or points of high resistance in circuit. (2) Voltage induced in secondary winding of ignition coil which is passed to spark plugs through distributor.
Highway engineer. One who plans the engineering work, design, and construction of modern highways.
High-wing monoplane. (Aero.) A monoplane whose wing is mounted directly at the top of the fuselage or above the fuselage.
Hinge. A mechanical device, con­sisting primarily of a pin and two plates, which may.be attached to the door and door frame to permit opening and closing of the door, or for use under any similar condi­tion.
Hip. (Arch.) The external joint usu­ally from eaves to. ridge between two parts of a sloping roof which approach each other at an angle, e.g., a joining or front and side roofs. The term is not applied to "ridge." Hip is the opposite of"val­ley" which is an interior angle.
Hip rafters. The rafters which form the hip of as roof; distinguished from ridge,
Hip roof. A roof which rises with equal angles from all four sides of a building.
Hob. (Mach.) A master cutter for cut­ting worm wheels and spur gears; also a master tap. (Plast.) A master model in hardened steel used to sink the shape of mold into a soft­steel block. (Arch.) A bracket in a fireplace on which a kettle may be hung.
Hobbing. Cutting the teeth of worm wheels, threads of dies, or chas­ers, with a hob or master tap.
Hock leg. (Furn.) A style of cabriole leg with a curve and angle on the underpan of the knee.
Hod. A long-handled receptacle for. carrying bricks and mortar.
Hoffman apparatus. (Chern. )An ap­paratus for the electrolysis of water.
Hogging. (Mach.) A term frequently used in machine-shop practice

Hook joint to Horse
deformation produced is propor­tional to the stress.
Hook joint. A dustproof joint for doors of showcases.
Hook rule. (Shopwk.) A rule with a projecting piece attached to one end at right angles to the balade.
Hook spanner. (Mach.) For use on round nuts notched on the peri­phery.
Hoop iron. The iron used for secur­ing the corners of packing cases.
Hopper. A box or receiver used for the purpose of feeding supplies of materials to machines or furnaces of various kinds.
Horizontal. In the direction of or arallel to the horizon; on a level.
Horizontal boiler. A boiler, the longitudinal axis of which is hori­zontal.
Horizontal boring machine. A machine tool having a horizontal spindle adjustable both vertically and longitudinally. The worktable is also adjustable and may be rotated, making the machine adaptable to a wide range of work.
Horizontal centering. (Tel.) The po­sition of a picture with respect to the axis of the cathode ray tube. This is accomplished by a control on the receiver.
Horizontal drill press. 'A drill press which operates horizontally instead of vertically.
Horizontal hold control. (Tel.) A con­trol on the receiver used to adjust the horizontal sweep oscillator so that it will synchronize with the synchornizing signals in the re­ceived picture signal.
Horizontal milling machine. A mill­ing machine with horizontal spin­dle and culler arbor. The table which can be raised and lowered to suit work conditions is capable of horizontal feed.
Horizontal return tubular boiler. (Ellgill.) A type of steel boiler con­sisting of a cylinderical sheet with fire tubes, enclosed in brick-work to form the furnace and combus­tion chamber.
Horn. (A era. ) A short lever attached to a control surface of an aircraft, to which the operating wire or rod is connected.
Hornblende. A common-, greenish­black or black mineral containing iron and silicate of magnesium, calcium, and aluminium.
Horn center. A small, transparent disk of horn used by draftsmen to place the points of their compasses upon when describing circles, to avoid piercing the paper itself. Not in very general use.
Horning press. (Mach.) Used for closing down side scams on sheet­metal receptacles, such as buckets. etc.
Horn relay. (Auto. Elec.) A mag­netic control introduced in a horn circuit. Pressure on horn button moves an armature into postion to close contact points so that full effect current passes directly to horn or horns.
Horology. The construction and repair of clocks, watches, etc. The science of time measurement.
Horse. (Bldg. alld Woodwkg.) (I) A trestle. (2) One of the slanting sup­ports. of 11 set of steps to which arc attached thc treads and risers.

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