400 STANDARD ELECTRICAL DICTIONARY.Pacinotti's Inductor.The Pacinotti or Gramme Ring. (See Pacinotti's Ring.)Pacinotti's Ring.A ring of iron wire wound with coils of insulated wire at right anglesto its circular axis, and used as the armature of a dynamo or motor. Anumber of connections are taken from the coils to a central commutator.Fig. 254. PACINOTTI'S MACHINE, WITH RING ARMATURE.If such a ring with its coils is rotated in a field, current can betaken from points of the commutator on a line at right angles to thelines of force entering the ring.The ring was discovered in 1862 by Pacinotti, and later wasindependently discovered by Gramme. It is often known as the Grammering.Pacinotti Teeth.Projections on a cylindrical or drum armature, between which in thegrooves formed thereby, the wire is wound. The teeth being of iron tendto diminish the reluctance or magnetic resistance of the interpolarspace, or interval between the poles of the field magnet.Synonym--Pacinotti Projections.Paillard Alloys.Non-magnetic palladium alloys, invented by Paillard, ofSwitzerland, used in anti-magnetic watches. The following are given asthe compositions of several such alloys:I. II.Palladium, 60 to 75 parts 50 to 75 partsCopper, I5 to 25 " 20 to 30 "Iron. 1 to 5 " 5 to 20 "401 STANDARD ELECTRICAL DICTIONARY.The following are more complex:I. II.Palladium, 65 to 75 parts 45 to 50 partsCopper, 15 to 25 " 15 to 25 "Nickel, 1 to 5 " 2 to 5 "Silver, 3 to 10 " 20 to 25 "Gold, 1 to 2-1/2 " 2 to 5 "Platinum, 1/2 to 2 " 2 to 5 "Steel, 1 to 5 " 2 to 5 "These alloys are used for balance springs, as well as for the balancewheels and escapement parts of watches. The elasticity of recentlyproduced springs has been found to be very satisfactory.Page Effect.The sounds produced by magnetizing and demagnetizing a bar of iron orsteel; the magnetic tick. The sounds are strong enough to produce atelephonic effect. (See Magnetic Tick.)Palladium.A metal of the platinum series. It has the highest power of occlusion,q.v., of all metals. It is the characteristic ingredient of non-magneticwatch alloys.Palladium used as an electrode in the electrolysis of water will occlude936 volumes of hydrogen, and the hydrogen-palladium alloy will exceed insize the original electrode.Fig. 255. LUMINOUS PANE.Pane, Luminous.A pane of glass, one side of which has pasted to it a long zigzag stripof tinfoil. A design is made by cutting through the strip. Ondischarging a Leyden jar or an electric machine through the strip sparksappear where the tinfoil is severed, thus producing the design in aluminous effect. Many variations can be employed in their construction.402 STANDARD ELECTRICAL DICTIONARY.Pantelegraphy.A system of telegraphy for transmitting designs, maps, drawing, and thelike by telegraphy. (See Telegraphy, Facsimile.)Paper Filaments.Filaments of carbon for incandescent lamps made from paper.This is one of the earliest materials practically used. The paper is cutout of proper shape, and is carbonized in a close vessel, while embeddedin powdered charcoal or some other form of carbon to absolutely cut offaccess of air. It is then placed in the lamp chamber and flashed orsubjected to the regular treatment.Parabola.A curve; one of the conic sections. It is approximately represented by asmall arc of a circle, but if extended becomes rapidly deeper than ahalf circle.If, from a point within called the focus, lines are drawn to the curveand then other lines are drawn from these points parallel to the axis,the angles of incidence will he equal to the angles of reflection asreferred to tangents at the points where the lines touch the curve.[Transcriber's note; The general equation of a parabola isA*x^2 + B*x*y + C*y^2 + D*x + E*y + F = 0such that B^2 = 4*A*C, all of the coefficients are real, and A and C arenot zero. A parabola positioned at the origin and symmetrical on the yaxis is simplified to y = a*x^2 ]Parabolic Reflector.A reflector for a light, a paraboloid or surface of revolution whosesection is a parabola. A light placed at its focus has its raysreflected parallel to each other.Examples of parabolic reflectors are seen in electric search lights andin locomotive head-lights. They are employed in electric search lights.The arc light must be of such construction as to maintain its ignitedpoints always at the same point, the focus of the paraboloid.Paraffine. v.To coat or saturate with paraffine wax. Paper may be paraffined bydipping in the wax, or by being sprinkled with fragments of wax,subsequently melted in with a hot iron or otherwise. The tops of batterycarbons are often paraffined to prevent the acid from rising in thepores by capillary attraction and rusting the connections.
403 STANDARD ELECTRICAL DICTIONARY.
Paraffine Wax.A hydro-carbon composed principally of mixtures of the higher members ofthe paraffine series C n H2 n + 2. It is made from cannel coal, coaltar, or petroleum by distillation. It is an insulator. Its resistance at46° C. (114.8° F.) per centimeter cube is 3.4E16 ohms, or about thehighest resistance known.Its specific inductive capacity (for milky wax) is 2.47 (Schiller). Forclear wax it is given as follows by different authorities:1.92 Ayrton.1.96 Wüllner.1.977 Gibson & Barclay.2.32 Baltzmann.It is extensively used in condensers and other electric apparatus as adielectric and insulator.Paragrêles.Protectors against hail; lightning rods used to guard fields againsthail; of little or no real utility.Parallax.The apparent change in position of an object when looked at from twopoints of view. By looking at an object a few feet distant first withone eye and then with the other, the shifting in apparent position isseen.In reading the position of an indicator or needle over a scale parallaxintroduces an error unless the eye is held vertically over the needle.By making the dial of looking- glass and holding the eye so that thereflection of its pupil is bisected by the needle this verticality isensured.Parallel.(a) In the nomenclature of electric circuits two or more conductorsleading from one point to another, are said to be in parallel.(b) When two or more conductors connect two main leads of comparativelylarge size and low resistance they are said to be in parallel or inmultiple arc. This order is easiest pictured as the rungs of a ladder inparallel connecting its two sides representing the main leads.It may be used as a noun as "arranged in parallel," or as an adjectiveas "a parallel circuit," the opposite of series, q. v.Paramagnetic. adj.Possessing paramagnetic properties; tending to occupy a position withthe longer axis parallel to the lines of force of a magnetic field;having magnetism; attracted by a magnet."If a homogeneous isotropic substance is placed in a magnetic field itbecomes magnetized at every point in the direction of the magneticintensity at that point, and with an intensity of magnetizationproportional to the magnetic intensity. When the positive direction ofthe induced magnetization is the same as that of the magnetic intensitythe substance is called Magnetic or Paramagnetic; when it is opposite,the substance is called Diamagnetic." (Emtage.)A paramagnetic substance has high permeability or multiplying power forlines of force, hence in a magnetic field a bar of iron, etc., is inunstable equilibrium unless its longer axis is parallel with the linesof force in order to reduce as much as possible the reluctance of thecircuit.404 STANDARD ELECTRICAL DICTIONARY.Iron is the most paramagnetic of all substances. Other paramagneticmetals are: Nickel, cobalt, manganese, platinum, cerium, osmium,palladium. Diamagnetic metals are bismuth, antimony, zinc, tin, mercury,lead, silver, copper, gold, arsenic. Bismuth is the most diamagnetic ofall metals.Of gases oxygen is most paramagnetic. Becquerel calculated that a cubicyard of oxygen condensed would act on a magnetic needle as powerfully as5.5 grains of metallic iron. Liquefied oxygen will adhere to the polesof a magnet.Changes of temperature and of other conditions may affect a body'smagnetism. Thus hot oxygen is diamagnetic, and a substance paramagneticin a vacuum may be diamagnetic in air.Of liquids, solutions of iron or cobalt are paramagnetic; water, blood,milk, alcohol, ether, oil of turpentine and most saline solutions arediamagnetic.Paramagnetism.(a) The science or study of paramagnetic substances and phenomena.(b) The magnetic property of a paramagnetic substance; that of beingattracted by a magnet, and of arranging itself with its longer axisparallel with the lines of force of a magnetic field.Parchmentizing.If cellulose is treated with a mixture of two parts of sulphuric acidand one part of water perfectly cold, it becomes like parchment. Itshould at once be washed with water, and then with ammonia and water.The Swan incandescent light fibres are made of parchmentized cottonthread, which is afterward carbonized.Partial Earth.A fault in a conductor caused by imperfect connection with the earth,where insulation from the earth is desired.Passive State.A state of a substance in virtue of which it is unattacked by a solventwhich ordinarily would dissolve or attack it. Iron in strong nitric acidis unattacked or assumes the passive state. This particular case issupposed to be due to a coating of magnetic oxide, so that there wouldbe properly speaking no question of a passive state, but only one ofsuperficial protection.The existence of a true passive state of any substance is very doubtful.P. D.Abbreviation for potential difference or difference of potential, or forelectro-motive force.405 STANDARD ELECTRICAL DICTIONARY.Peltier Effect.The thermal effect produced by the passage of a current through thejunction of two unlike conductors. Such junction is generally the seatof thermo-electric effects, and a current is generally produced byheating such a junction. If an independent current is passed in the samedirection as that of the thermoelectric current, it cools the junction,and warms it if passed in the other direction. In general terms,referring to thermo-electric couples, if passed through them it tends tocool the hot and heat the cool junction. The phenomenon does not occurin zinc-copper junctions.Peltier's Cross.A bar of bismuth and a bar of antimony soldered centre to centre atright angles, being notched or halved there to receive or to set intoeach other. It is used to demonstrate the Peltier effect, q. v. To onepair of ends are connected the terminals of a battery circuit; to theother pair are connected the terminals of a galvanometer.The galvanometer by its deflections in one and then in the otherdirection indicates that the junction is heated when the current passesfrom antimony to bismuth and vice versa. It thus illustrates the heatingand cooling of a thermo-electric junction by a current of electricity.The current from the battery by the Peltier effect either heats or coolsthe junction, as the case may be. This heating or cooling them producesa thermo-electric current in the galvanometer circuit. The battery hasno direct influence on the galvanometer.Pendant Cord.A double conductor or pair of conductors, insulated from each other andcovered with a worsted, silk, or cotton covering and used to suspendincandescent lamps and at the same time to conduct the current to them.It is also used for other similar service, such as acting as conductorsfor small motors. Often each conductor is composed of a number of thinwires laid together. This gives flexibility to the cord.Synonym--Flexible Cord.Pendulum, Electric.(a) A pendulum operated by the intermittent action of an electro-magnet,whose circuit is opened and closed by the pendulum itself. A point atthe lower end of the pendulum swinging through a globule of mercury mayclose and open the circuit. Various other methods of accomplishing thesame end are employed ..(b) A pith ball suspended by a thread from an insulating stand. It isused to show the attraction exercised by a piece of sealing wax or othersubstance excited by rubbing.406 STANDARD ELECTRICAL DICTIONARY.Pen, Electric.A stylus for producing a series of perforations in paper, so that thepaper may act as a stencil for the reproduction of a great number ofcopies of the original matter. Various kinds of electric pens have beeninvented. One kind, invented by Edison, consists of a handle carrying anelectric motor actuating a needle, which is driven in and out of theother end of the handle with high rapidity. It is used by being heldvertically on the paper with the needle end downward, and is moved so asto describe perforated letters or designs. The paper is then used as astencil with an ink roller to reproduce the writing or design adlibitum. A simpler kind dispenses with the motor and depends on theperforations produced by the electric spark. As shown in the cut thestylus is one terminal of an induction coil circuit. The support onwhich the paper rests is the other terminal and must be a conductor. Inuse the induction coil is started, and the stylus is moved over thepaper; a series of sparks pass through the paper from stylus to thesupporting tablet, perforating the paper and producing a stencil to beused for reproduction.Fig. 256. ELECTRIC PEN.Pentane Standard, Harcourt's.A standard of illuminating power; in it the combustible substance is agas made by mixing one cubic foot of air with three cubic inches ofliquid pentane, measured at 60° F. or, if measured as gases, 20 volumesof air to 7 of pentane. It is burned at the rate of 0.5 cubic foot perhour from a cylindrical tube one inch in diameter, closed at the top bya disc 0.5 inch thick with a hole 0.25 inch in diameter, through whichthe gas issues. It gives a flame 2.5 inches high.The pentane used is the distillate of petroleum which boils at 50° C.(122° F.) ; it has a specific gravity at 15° C. (60° F.) of from 0.628to 0.631. It is almost pure pentane (C5H12).As long as the rate of consumption is between 0.48 and 0.52 cubic footper hour the flame gives practically the same light.407 STANDARD ELECTRICAL DICTIONARY.Perforator.An apparatus used in automatic high speed telegraphy for perforatingstrips of paper. These are then used by drawing between a roller andcontact spring for making and breaking the telegraphic circuit for theproduction of a record, such as the Morse record, at the distantreceiving station.The perforated strip has different classes of holes punched in it torepresent dots or dashes. It is fed by machinery very rapidly, so thatthe message is transmitted with the highest speed. Several operators maysimultaneously prepare the paper strips, and thus in conjunction withits rapid feeding in the transmitter, far surpass the time of ordinarydirect transmission.Fig. 257. PERFORATOR FORWHEATSTONE'S AUTOMATIC TELEGRAPH.Perforators may be entirely mechanical but are sometimes pneumatic,compressed air being used to operate them. The holes they make are ondifferent levels of the paper strip, as shown in the cut.Period.The time required for the completion of one complete element of periodicmotion. This may be a complete alternation (See Alternation, Complete)of an alternating current, or of an oscillatory discharge.Periodicity.The rate of succession of alternations or of other fixed phases; therate of recurrence of phenomena.408 STANDARD ELECTRICAL DICTIONARY.Permanency.In electric current conductors the property of possessing conductivityunaffected by lapse of time. Generally the permanency of conductors isvery high. In some cases a slow annealing takes place which causes agradual change with the lapse of time. Annealed German silver wire hasbeen found to increase in conductivity at about .02 per cent. in a year.(Matthiessen.) Wire, whether annealed or not, is left in a strainedcondition after the drawing operations, and such a change is consonantwith this fact. The figure only applies to the samples tested byMatthiessen.Permanent State.In a telegraph line or other current conductor, the condition when auniform current strength obtains over the whole line. When a current isstarted it advances through the line with a sort of wave front graduallyincreasing in strength. At the further end some time may elapse beforeit attains its full intensity. When its does the permanent stateprevails. Until then the variable state, q. v., exists in the line.Permeameter.An apparatus for determining the permeability of samples of iron. Itconsists of a large slotted block of iron. A coil is placed within theslot. A hole is drilled through one end, and a rod of the iron to betested is passed through this hole and through the coil to the bottom ofthe slot. The lower end of the rod must be accurately faced off. Thecurrent is turned on, upon which the rod adheres to the bottom of theslot. The force required to detach it is determined with a springbalance. The permeation through its face is proportional to the squareof the force required.Fig. 258. PERMEAMETER.Permeance.The multiplying or the conducting power for magnetic lines of forcepossessed by a given mass of material. It varies with the shape and sizeof the substance as well as with the inducing force. It is distinguishedfrom permeability, as the latter is a specific quality proper to thematerial, and expressed as such; the permeance is the permeability asaffected by size and shape of the object as well as by its material.409 STANDARD ELECTRICAL DICTIONARY.Pflüger's Law.A law of electro-therapeutics. It states that stimulation of a nerve isonly produced by successive appearance of the kathelectrotonic state,and disappearance of the anelectrotonic state.Phantom Wires.The extra transmission circuits obtained in multiplex telegraph systems.A single line arranged for four separate simultaneous transmissions byquadruplex apparatus is said to establish three phantom wires.Phase.In wave motion, oscillating motion, simple harmonic motion, or similarperiodic phenomena, the interval of time passed from the time the movingparticle moved through the middle point of its course to the instantwhen the phase is to be stated.Pherope.An apparatus for the electric transmission of pictures. (See Telephote.)[Transcriber's note: Precursor of the contemporary Fax and scanner.]Philosopher's Egg.An ellipsoidal vessel mounted with its long axis vertical and with twovertical electrodes, the upper one sliding, and arranged to be attachedto an air pump. A discharge through it when the air is exhausted takesthe general shape of an egg.Phonautograph.An apparatus for registering the vibrations of a stylus, which ismounted on a diaphragm and is acted on by sound waves.It is virtually a resonating chamber, over one of whose ends a parchmentdiaphragm is stretched. To the centre of the parchment a needle orstylus is attached. A cylinder covered with soot is rotated in contactwith the point of the stylus. As the chamber is spoken into thediaphragm and stylus vibrate and the vibrations are marked on thecylinder. It is of some electric interest in connection with telephony.Phone.Colloquial abbreviation for telephone.Phonic Wheel.A form of small motor of very simple construction. It consists of atoothed wheel of soft iron. A bar electro-magnet is fixed with one polefacing the teeth of the wheel. By a tuning fork make and break asuccession of impulses of rapid frequency and short duration are sentthrough the magnet. The teeth act as armatures and are successivelyattracted by the magnet. The regulated speed is one tooth for eachimpulse, but it may rotate at one-half the speed, giving two teeth foreach impulse, or at certain other sub-multiples of its regular speed. Itis the invention of Paul Lecour.410 STANDARD ELECTRICAL DICTIONARY.Phonograph.An apparatus for reproducing articulate speech. It is not electric,except as it may be driven by electricity.It consists of a cylinder of wax-like material which is rotated andmoved slowly, longitudinally, screw fashion, at an even speed. A glassdiaphragm carrying a needle point is supported with the point barelytouching the wax. If the diaphragm is agitated, as by being spokenagainst, the needle is driven back and forwards cutting a broken line orgroove following the direction of the thread of a screw in the wax, thedepth of which line or groove continually varies.This imprints the message. If the needle is set back and the cylinder isrotated so as to carry the needle point over the line thus impressed,the varying depth throws the needle and diaphragm into motion and thesound is reproduced.The cylinder is rotated often by an electric motor, with a centrifugalgovernor.[Transcriber's note; Due to T. A. Edison, 1877, fifteen years beforethis book.]Phonozenograph.An apparatus for indicating the direction of the point where a sound isproduced. It operates by a microphone and telephone in conjunction witha Wheatstone bridge to determine the locality.Phosphorescence.The emission of light rays by a substance not heated, but whoseluminosity is due to the persistence of luminous vibration after lighthas fallen upon it.A phosphorescent body, after exposure to light, is luminous itself.Phosphorescence may be induced by rubbing or friction, by heat, bymolecular bombardment, as in Crookes' tubes, and by static discharge ofelectricity, as well as by simple exposure to light.Another form of phosphorescence may be due to slow chemical combustion.This is the cause of the luminosity of phosphorous.Phosphorous, Electrical Reduction of.Phosphorous is reduced from bone phosphate by the heat of the electricarc. The phosphate mixed with charcoal is exposed to the heat of thevoltaic are, and reduction of the phosphorous with its volatilization atonce ensues. The phosphorous as it volatilizes is condensed andcollected.Photo-electricity.The development of electrical properties by exposure to light. Crystalsof fluor spar are electrified not only by heat (see Pyro-electricity)but also by exposure to sunlight or to the light of the voltaic arc.[Transcribers note: Although first observed in 1839 by Becquerel, itwas not explained until 1905 by Albert Einstein with the introduction ofphotons.]Photo-electric Microscope.A projection, solar or magic-lantern microscope worked by the electriclight.Photo-electro-motive Force.Electro-motive force produced in a substance by the action of light.411 STANDARD ELECTRICAL DICTIONARY.Photometer.An apparatus for measuring the intensity of light emitted by a givenlamp or other source of illuminating power. They may be classified intoseveral types.Calorimetric or Heat Photometers act by measuring relatively the heatproduced by the ether waves (so-called radiant heat) emitted by thesource. The accuracy of the instrument is increased by passing the raysthrough an alum solution. A thermopile, or an air thermometer, may beused to receive the rays.Chemical Photometers. In these the light falls upon sensitizedphotographic paper. The depth of coloration is used as the index ofilluminating power.Direct Visual Photometers. These include Rumford's Shadow Photometer,Bunsen's Bar Photometer, and Wheatstone's Bead Photometer, in which thelight is estimated by direct visual comparison of its effects.Optical Photometers. These include Polarization Photometers, in whichthe light is polarized; Dispersion Photometers, in which a diverginglens is placed in the path of the rays of light so as to reduce theilluminating power in more rapid ratio than that of the square of thedistance.Selenium Photometers, in which the variations in resistance of seleniumas light of varying intensity falls upon it is used as the indicator ofthe intensity of the light.Jet Photometers, for gas only, in which the height of a flame undergiven conditions, or the conditions requisite to maintain a flame ofgiven height, is used to indicate the illuminating power.The subject of photometers has acquired more importance than ever inview of the extensive introduction of the electric light. (See Candle,Standard--Carcel--Violé's Standard--and Photometers of various kinds.)Photometer, Actinic.A photometer whose registrations are produced by the action of the lightbeing tested upon sensitized paper or plates, such as used inphotography. Some efforts at self-registering photometers have beenbased on actinic registration of the height of a flame of the gas to betested.Photometer, Bar.A photometer in which the two lights to be compared are fixed at oropposite to the ends of a bar or scale of known length, generally 60 or100 inches. The bar is divided by the rule of the inverse square of thedistances, so that if a screen is placed on any part of the bar where itreceives an equal amount of light from both sources, the figure on thebar will indicate the relative illuminating power of the larger lamp orlight in terms of the smaller. The divisions of the bar are laid out onthe principle that the illuminating power of the two sources of lightwill vary inversely with the square of their distance from the screen.412 STANDARD ELECTRICAL DICTIONARY.The screen used is sometimes the Bunsen disc. This is a disc of paperwith a spot of paraffine wax in the centre melted thoroughly into thepaper or with a ring of paraffine wax surrounding the untouched centre.When this disc is equally illuminated on both sides the spot is nearlyinvisible. Inequality of illumination brings it out more visibly.Sometimes a Leeson disc is used. This consists of three pieces of paper,two thin ones between which a thicker piece, out of which a star is cut,is laid. When equally illuminated on both sides the star appears equallybright on both sides.The bar photometer is the standard form. A candle or pair of candles maybe burned at one end and an incandescent lamp at the other, or a gasflame may first be rated by candles and used as a standard.Synonyms--Bunsen's Photometer--Translucent Disc Photometer.Fig. 259. BAR PHOTOMETER.Photometer. Calorimetric.A photometer in which the radiant energy, so called radiant heat, isused as the measurer of the light.In one type a differential air thermometer is used, one of whose bulbsis blackened. On exposing this bulb to a source of light it will becomeheated, and if lights of the same character are used the heating will bein proportion to their illuminating power quite closely. The heating isshown by the movements of the index. By careful calibration theinstrument may be made quite reliable.Photometer, Dispersion.A photometer in which the rays from one of the lights under comparisonare made more divergent by a concave lens. In this way a strong light,such as all arc lamp can be photometered more readily than where onlythe natural divergence of the beam exists. The law of the variation ofthe intensity of light with the square of the distance is abrogated fora law of more rapid variation by the use of a concave lens.The diagram, Fig. 260, illustrates the principle. E represents apowerful light, an arc light, to be tested. Its distance from the screenis e. Its light goes through the concave lens L and is dispersed asshown over an area A1, instead of the much smaller area A, which thesame rays would otherwise cover. Calling l the distance of the lens fromthe screen, f its focus, and c the distance of the standard candle fromthe screen when the shadows are of equal intensity, we have theproportion.
Illuminating power of lamps: ditto of standard candle::(l (e-l) + fe)2 : (c f)2