LIST OF ILLUSTRATIONS.
| Frontispiece—Complete Wiring Plan for a House. | ||
| [1] | Diagram of Simple Circuit | 2 |
| [2] | Diagram of Simple Circuit with Spiral | 2 |
| [3] | Diagram of Simple Circuit with Spiral and Galvanometer | 2 |
| [4] | Diagram of Circuit with Iron Core | 4 |
| [5] | Diagram of Ruhmkorff Coil | 4 |
| [6] | Elevation of Ruhmkorff Coil | 6 |
| [7] | Pendant Burner | 7 |
| [8] | Burner Circuit | 8 |
| [9] | Plain Burner | 10 |
| [10] | Ratchet Burner | 11 |
| [11] | Stiff-Pull Pendant | 12 |
| [12] | Stem Burner | 14 |
| [13] | Argand Burner | 15 |
| [14] | Welsbach Burner | 16 |
| [15] | Acetylene Burner | 17 |
| [16] | Push Button | 19 |
| [17] | Bartholdi Burner | 21 |
| [18] | Boston Automatic | 22 |
| [19] | Concealed Automatic | 24 |
| [20] | Diagram Wiring One “Automatic” from Two Pushes | 27 |
| [21] | Diagram Wiring One “Automatic” and Two Pendant Burners | 28 |
| [22] | Simple Switch Connections | 33 |
| [23] | Details of Automatic Connections | 35 |
| [24] | Details of Cellar Automatic Circuits | 35 |
| [25] | Nut Wrench | 40 |
| [26] | Automatic Operated by Door-Trip | 44 |
| [27] | Primary Coil | 46 |
| [28] | Syracuse Cut-Out | 50 |
| [29] | Boston Cut-Out | 51 |
| [30] | Details Cut-Out Rod—Normal | 52 |
| [31] | Details Cut-Out Rod—Operating | 53 |
| [32] | Bulb Cut-Out | 54 |
| [33] | Jump Spark Burner | 56 |
| [34] | Welsbach Burner for Series Lighting | 56 |
| [35] | Pillar Burner | 56 |
| [36] | Circuit For Jump Spark Gas Lighting | 57 |
| [37] | Insulator | 59 |
| [38] | Edwards’ Condenser | 60 |
| [39] | Edwards’ Burner | 61 |
| [40] | Edwards’ Burner | 61 |
| [41] | Diagram of Edwards’ Condenser Circuit | 62 |
| [42] | Circuit for Jump Spark Switch | 64 |
| [43] | Electromagnetic Trailer | 66 |
| [44] | Diagram of Ruhmkorff Coil Circuit | 68 |
| [45] | Windings of Sections | 73 |
| [46] | Sectional Diagram | 74 |
| [47] | Contact Breaker | 75 |
| [48] | Contact Key | 76 |
| [49] | Fall of Potential Diagram | 79 |
| [50] | Series Arrangement | 81 |
| [51] | Multiple Arrangement | 82 |
| [52] | Leclanche Cell | 84 |
| [53] | Samson Cell | 87 |
| [54] | New Standard Cell | 90 |
| [55] | Edison-Lalande Cell | 92 |
| [56] | Fuller Cell | 94 |
| [57] | Grenet Cell | 95 |
CHAPTER I.
Introductory Remarks.
The enormous number of fires arising from the use of matches, and the great convenience and freedom from danger of the electric method of gas lighting, are alone sufficient reasons for the issue of these pages.
The veriest tyro in electrical operations knows that electricity will cause a spark, and most persons are aware that the spark possesses considerable deflagratory powers, varying with the character of the spark. In electric gas lighting a spark of the proper character is passed across a jet of gas and ignites it. Sparks can be produced by various means: friction, battery current, induction either galvanic or electro-magnetic, by a Wimshurst or Toepler Holtz machine, or an induction coil operated by a battery. For our purposes we will consider only the latter; the former are rarely used, being uncertain and unwieldy.
Of batteries there are many kinds, and although all will produce sparks, yet for electric gas lighting those made for intermittent work and classed as open circuit cells are to be preferred. Open circuit batteries, which will be fully described in a subsequent chapter, include the Leclanche, and most of the so-called “dry” cells.
Fig. 1., Fig. 2., & Fig. 3.
If two wires be attached to a cell of battery B, one to the carbon or positive pole and the other to the zinc or negative pole, and their free ends be tapped together, minute sparks at C will be observed each time the wires separate (Fig. 1). If now a coil of insulated wire S be included in the circuit, Fig. 2, upon repeating the make and break of contact, the sparks will be much increased. This arises from induction, each adjacent turn of wire acting upon its neighbor. To better understand the action of induction, we will consider the following examples: Fig. 3. A is a circuit in which is the battery cell B. C is a second circuit lying close to but well insulated from circuit A. G is a galvanometer in which a magnetized needle swings right or left each time a current is passed through a coil of wire encircling it. Now, although there is no battery cell in circuit C, yet the needle will swing each time the circuit A is closed or opened; that is, each time the wire ends are touched together or separated. This swing of course indicates that a current is passing through circuit C, but as there is no battery or other source of electrical energy included in it, it is clear that it arises from the action of the current in circuit A. In point of fact, the needle swings one way when the circuit is closed and the reverse way when it is opened; but the greater swing on opening the circuit indicates the greater strength of the induced current at the moment the current ceases to flow in circuit A. Note that these current impulses are only momentary. In the case of our single coil, Fig. 2, each turn of wire acted upon itself in a similar manner to the circuit A upon circuit C.
Fig. 4., & Fig. 5.
An iron rod or bundle of iron wires, P, inserted in the coil, Fig. 4, but carefully insulated from it, will immensely increase the inductive effects and consequently the spark. This arrangement constitutes the simple primary coil used in pull-down or pendant and automatic burners. This spark is often a source of inconvenience; it appears wherever a circuit including similar coils is made and broken. In telegraph apparatus at key and relay contacts it is noticeable; in fact, the writer has used temporarily a pair of electro-magnets from a telegraph sounder and obtained spark enough to operate a gas lighting burner.
To produce a long spark which will jump across an air gap, a more complicated form of coil is needed, one which more closely corresponds to the experiment noted in Fig. 3. The simple primary coil has here another coil of finer wire, S, wound on it but carefully insulated from it (Fig. 5). This second coil, or “secondary,” has a vast number of turns of fine wire as compared with the primary, which has only comparatively few turns of coarse wire. A primary coil of 40 feet of No. 14 B. & S. copper wire would be inserted in a secondary coil of perhaps 16,000 feet of No. 36 B. & S. This secondary coil, in fact all the apparatus constituting the induction coil, must be most highly insulated, as the electromotive force of the spark is tremendous, and it would be liable to pierce its way through and into the internal winding and so destroy the apparatus. The circuit in the primary is made and broken either by a hand key or by an automatic contact-breaker at C. With a large coil, the intensity of the spark at G is such that it will jump an air-gap of from one-eighth of an inch to over three feet.[A]
[A] See Norrie, Induction Coils and Coil-Making.
This combination of coils and contact-breaker is generally known as a Ruhmkorff or intensity coil, and is shown in elevation in Fig. 6.
Fig. 6.
CHAPTER II.
Multiple Gas Lighting.
Fig. 7.
As we have already seen how a spark is exhibited at an interrupted contact, the means of its application to gas lighting will be considered. Fig. 7 represents the most generally used kind of electric gas burner or “pendant burner.” Its application is shown in Fig. 8. The wire W from the coil C is attached to the brass insulated collar carrying the contact S. The other wire from coil C and battery B is attached to the gas pipe G. As the burner is also screwed into the gas pipe itself, the circuit would be closed were it not for the gap at A on the burner, caused by the collar carrying the contact C and wire W, being insulated from the burner pillar P. When, however, a pull is given to the burner arm chain so as to cause the end of the spring R to strike contact C in passing, contact is made and broken, and a spark passes which ignites the gas issuing from the burner tip, the gas having previously been turned on. A piece of chain with a metal ball is attached to the burner arm in order to pull it down. In this class of burner there are many different makes differing only in minor details.
Fig. 8.
Fig. 9 shows a form of pendant burner which has no platinum contact, but has a broad lug on the insulated collar which is scraped against by the spiral spring when the arm is pulled down. It will be seen that the lug is not held by an insulated collar on the burner top, but is on the extension of an arm attached to the burner pillar by a large screw and insulating washers. The circuit wire goes under the smaller screw seen on the lower part of the contact arm, this forming a strong and neat form of attachment.
Fig. 9.
Now it has heretofore been necessary to turn on the gas before pulling the chain of a pendant burner, but as this is not always desirable the ratchet burner is made. Fig. 10 shows burner carrying a toothed wheel, which is partly rotated when the arm is pulled down. This wheel is mounted on the stem of a valve which opens or shuts according to the point of rotation, and thus shuts off or admits the gas to flow up to the burner. One pull of the arm turns the gas on; at the same time the wipe spring touches the contact on burner collar, and the gas lights. A second pull and the wheel, rotating, turns off the gas. In all burners of this class a spring is provided to carry the arm up and back into its original position ready for another pull. Some burners do not make contact when the arm flies back, thus saving battery current.
Fig. 10.
Fig. 11.
Fig. 11 is an improved form of burner wherein the movable electrode does not pass through the gas flame, neither do the electrodes come in contact with each other when the gas is being turned off. Reference to the cut will show a pin protruding from the base of the coiled spring electrodes, which pin is so arranged as to come in contact with the short end of the pull-arm. When this pull-arm is pulled down it pushes up this pin, elongating the spiral spring electrode sufficiently to make and break contact at the fixed electrode on the burner collar. This burner can be fitted with a porcelain candle slip if desired to match the imitation candle burners.