O gee to Oleo gear

O -gee to OU gauge

O-gee. (Arch.) A molding having in section a reverse curve or long curve.

Ogive. (Furn.) A pointed arch. Ohum. The meter-kilogram-second unit of resistance equal to the re­sistance in a conductor in which one volt of potential difference produce a current of one ampere.

Ohmic contact. An electrical contact in which the potential difference across it is proportional to the cur­rent flowing through it.

Ohmmeter. (Elec.) A type of galva­nometer which directly indicates the number of ohms of the resis tance being measured. .

Ohm resistance. (Elec.) A circuit (d.c.) is said to have a resistance of one ohm when one volt (e.m.f.) will produce a current of one am­pere through it.

Ohm's law. (Elec.) A law which states that the current flowing in a circuit is proportional to the e.m.f. and inversely proportional to the resistance or opposition. More frequently it is expressed in mathematical form :

Oil. ( Chern.) A greasy or unctuous liq­uid of animal, vegetable, or min eral origin; in addition to its use as a lubricant, oil has a very wide use in the industries.

Oil bloom. (Paint and lAcquer) Iri­descent appearance generally due to rubbing or polishing with. a material that contains free oil which floats to surface of film.

Oil control ring. (Auto.) A type of piston ring designed to scrape from the cylinder wall, oil which passes through slots in the ring and small holes in the piston wall, and then drains to the crankcase. Such rings are usually placed next above the piston-pin bosses.

Oil cup. (Mach.) Consists of a hol­low glass cylinder contained be­tween brass top and bottom plates, so designed that it may be attached by screw threads to a bearing; used to permit a constant and uniform dripping of oil when desired..

Oiler. A small-size oil can.

Oil filter. (Auto.) The cylinder con­taining screens or fi1tering mate­rial, attached to the motor in such a manner that when the motor is running, the lubricating oil is con­stantly passing through the filter, thus removing grit and foreign matter. The filtering unit should be renewed at every 8,000 miles.

Oil gauge. (Auto.) These gauges are of two kinds; one is used to indi­cate the amount of oil in the sump; the other indicates the pressure of flow of the oil. An oil pressure gauge usually is mounted On the instrument board and indicates the amount of pressure by the positio.n~

Oil grinder to Oleo gear of a hand on a graduated dial.

Oil grinder. (Wood Patrnkg.) A type of power-drivern grinder used for grinding plane bits and other edged tools.

Oil groove. (Mech.) Small, semicir­cular groove, cut in the internal face of a brass and on the sliding surface of machinery, for the dis­tribution of oil for lubricating pur­poses.

Oil hardening. (Mech.) The harden­ing of steel by quenching it if) oil instead of water.

Oil hole. (Mach.) A hole through which oil is admitted to a bearing.

Oil-hole drills. (Mata/wk.) Drills with one or two oil holes running from shank to cutting point; used principally for drilling deep holes.

Oilless type bearings. (Auto.) (I) Bearings which require oiling only at long intervals. Usually made of some oil-absorbing porous metal. The warmer the bearing, the more actively it lubri­cates. (2) Bronze bearings with graphite iI:lserts.

Oil line. (Auto. ~ The tubing and devices cgnnected therewith which com­prise the circuit for lubricating oil.

Oil pan. (Auto.) The lower half of the crankcase, made either of pressed steel or cast aluminium.

Oil pump. (Auto.) Oil pumps are of the gear" vane, or plunge~ type.They are usually an integral part of the engine. Their purpose is to lift oil from the sump to the upper level in the splash and circulating system, and in forced-feed lubri­cation they pump the oil to the tubes leading to the bearings and other parts.

Oilslip. (Wood wkg.) A small un­mounted oilstone held in the hand while whetting the cutting edges of gouges.

Oilstone. (Woodwkg.) A smooth stone used, when moistened with oil, for sharpening tools, etc.'

Oil-tank vent. (Aero.) A large tube used to conduct oil vapours from the engine to the oil tank.

Oil tannage. (Leather.) The oldest tanning method of which there is any record. The present method consists of kneading the skins in contact with certain oils and soft . fats. Oil tannage is used in the manufacturer of chamois, buff, and buck leathers.

Oil tight. Constructed or packed so as to prevent oil leakage.

Oil varnish. (Wood Fin.) Contains drying oirs such as linseed oil and tung oil. The hardening process . takes place slowly through oxida­tion.

Old man. (Shopwk.) A shop term ap­plied to a portable frame or sup­port, used in connection with a ratchet drill, for drilling "in the field" or "on the job."

Old style. (Print.) A type face dis­tinguished by oblique serifs; used during the eighteenth century.

Oleaginous. (Chern.) Oily; pretaining to oil.

Ole-fine. (Chern.) A member of the ethylene series.

Oleo gear. (Aero.) An oil-damping