On this short stretch of road there were many sharp curves and steep grades, and in consequence of the high speed attained (as high as forty-two miles an hour) several derailments took place, but fortunately without serious results. Three cars were in service during the entire time of operating this 1880 railroad: one a flat-car for freight; one an open car with two benches placed back to back; and the third a box-car, familiarly known as the "Pullman." This latter car had an interesting adjunct in an electric braking system (covered by Edison's Patent No.

248,430). "Each car axle had a large iron disk mounted on and revolving with it between the poles of a powerful horseshoe electromagnet. The pole-pieces of the magnet were movable, and would be attracted to the revolving disk when the magnet was energized, grasping the same and acting to r.e.t.a.r.d the revolution of the car axle."

Interesting articles on Edison's first electric railroad were published in the technical and other papers, among which may be mentioned the New York Herald, May 15 and July 23, 1880; the New York Graphic, July 27, 1880; and the Scientific American, June 6, 1880.

Edison's second electric railroad of 1882 was more pretentious as regards length, construction, and equipment. It was about three miles long, of nearly standard gauge, and substantially constructed. Curves were modified, and grades eliminated where possible by the erection of numerous trestles. This road also had some features of conventional railroads, such as sidings, turn-tables, freight platform, and car-house. "Current was supplied to the road by underground feeder cables from the dynamo-room of the laboratory. The rails were insulated from the ties by giving them two coats of j.a.pan, baking them in the oven, and then placing them on pads of tar-impregnated muslin laid on the ties. The ends of the rails were not j.a.panned, but were electroplated, to give good contact surfaces for fish-plates and copper bonds."

The following notes of Mr. Frederick A. Scheffler, who designed the pa.s.senger locomotive for the 1882 road, throw an interesting light on its technical details:

"In May, 1881, I was engaged by Mr. M. F. Moore, who was the first General Manager of the Edison Company for Isolated Lighting, as a draftsman to undertake the work of designing and building Edison's electric locomotive No. 2.

"Previous to that time I had been employed in the engineering department of Grant Locomotive Works, Paterson, New Jersey, and the Rhode Island Locomotive Works, Providence, Rhode Island....

"It was Mr. Edison's idea, as I understood it at that time, to build a locomotive along the general lines of steam locomotives (at least, in outward appearance), and to combine in that respect the framework, truck, and other parts known to be satisfactory in steam locomotives at the same time.

"This naturally required the services of a draftsman accustomed to steam-locomotive practice.... Mr. Moore was a man of great railroad and locomotive experience, and his knowledge in that direction was of great a.s.sistance in the designing and building of this locomotive.

"At that time I had no knowledge of electricity.... One could count so-called electrical engineers on his fingers then, and have some fingers left over.

"Consequently, the ELECTRICAL equipment was designed by Mr. Edison and his a.s.sistants. The data and parts, such as motor, rheostat, switches, etc., were given to me, and my work was to design the supporting frame, axles, countershafts, driving mechanism, speed control, wheels and boxes, cab, running board, pilot (or 'cow-catcher'), buffers, and even supports for the headlight. I believe I also designed a bell and supports. From this it will be seen that the locomotive had all the essential paraphernalia to make it LOOK like a steam locomotive.

"The princ.i.p.al part of the outfit was the electric motor. At that time motors were curiosities. There were no electric motors even for stationary purposes, except freaks built for experimental uses. This motor was made from the parts--such as fields, armature, commutator, shaft and bearings, etc., of an Edison 'Z,' or 60-light dynamo. It was the only size of dynamo that the Edison Company had marketed at that time.... As a motor, it was wound to run at maximum speed to develop a torque equal to about fifteen horse-power with 220 volts. At the generating station at Menlo Park four Z dynamos of 110 volts were used, connected two in series, in multiple arc, giving a line voltage of 220.

"The motor was located in the front part of the locomotive, on its side, with the armature shaft across the frames, or parallel with the driving axles.

"On account of the high speed of the armature shaft it was not possible to connect with driving-axles direct, but this was an advantage in one way, as by introducing an intermediate counter-shaft (corresponding to the well-known type of double-reduction motor used on trolley-cars since 1885), a fairly good arrangement was obtained to regulate the speed of the locomotive, exclusive of resistance in the electric circuit.

"Endless leather belting was used to transmit the power from the motor to the counter-shaft, and from the latter to the driving-wheels, which were the front pair. A vertical idler-pulley was mounted in a frame over the belt from motor to counter-shaft, terminating in a vertical screw and hand-wheel for tightening the belt to increase speed, or the reverse to lower speed. This hand-wheel was located in the cab, where it was easily accessible....

"The rough outline sketched below shows the location of motor in relation to counter-shaft, belting, driving-wheels, idler, etc.:

"On account of both rails being used for circuits, . . . the driving-wheels had to be split circ.u.mferentially and completely insulated from the axles. This was accomplished by means of heavy wood blocks well sh.e.l.lacked or otherwise treated to make them water and weather proof, placed radially on the inside of the wheels, and then substantially bolted to the hubs and rims of the latter.

"The weight of the locomotive was distributed over the driving-wheels in the usual locomotive practice by means of springs and equalizers.

"The current was taken from the rims of the driving-wheels by a three-p.r.o.nged collector of bra.s.s, against which flexible copper brushes were pressed--a simple manner of overcoming any inequalities of the road-bed.

"The late Mr. Charles T. Hughes was in charge of the track construction at Menlo Park.... His work was excellent throughout, and the results were highly satisfactory so far as they could possibly be with the arrangement originally planned by Mr. Edison and his a.s.sistants.

"Mr. Charles L. Clarke, one of the earliest electrical engineers employed by Mr. Edison, made a number of tests on this 1882 railroad. I believe that the engine driving the four Z generators at the power-house indicated as high as seventy horse-power at the time the locomotive was actually in service."

The electrical features of the 1882 locomotive were very similar to those of the earlier one, already described. Shunt and series field-windings were added to the motor, and the series windings could be plugged in and out of circuit as desired. The series winding was supplemented by resistance-boxes, also capable of being plugged in or out of circuit. These various electrical features are diagrammatically shown in Fig. 2, which also ill.u.s.trates the connection with the generating plant.

We quote again from Mr. Hammer, who says: "The freight-locomotive had single reduction gears, as is the modern practice, but the power was applied through a friction-clutch The pa.s.senger-locomotive was very speedy, and ninety pa.s.sengers have been carried at a time by it; the freight-locomotive was not so fast, but could pull heavy trains at a good speed. Many thousand people were carried on this road during 1882."

The general appearance of Edison's electric locomotive of 1882 is shown in the ill.u.s.tration opposite page 462 of the preceding narrative. In the picture Mr. Edison may be seen in the cab, and Mr. Insull on the front platform of the pa.s.senger-car.

XIV. TRAIN TELEGRAPHY

WHILE the one-time art of telegraphing to and from moving trains was essentially a wireless system, and allied in some of its principles to the art of modern wireless telegraphy through s.p.a.ce, the two systems cannot, strictly speaking be regarded as identical, as the practice of the former was based entirely on the phenomenon of induction.

Briefly described in outline, the train telegraph system consisted of an induction circuit obtained by laying strips of metal along the top or roof of a railway-car, and the installation of a special telegraph line running parallel with the track and strung on poles of only medium height. The train, and also each signalling station, was equipped with regulation telegraph apparatus, such as battery, key, relay, and sounder, together with induction-coil and condenser. In addition, there was a special transmitting device in the shape of a musical reed, or "buzzer." In practice, this buzzer was continuously operated at a speed of about five hundred vibrations per second by an auxiliary battery. Its vibrations were broken by means of a telegraph key into long and short periods, representing Morse characters, which were transmitted inductively from the train circuit to the pole line or vice versa, and received by the operator at the other end through a high-resistance telephone receiver inserted in the secondary circuit of the induction-coil.

The accompanying diagrammatic sketch of a simple form of the system, as installed on a car, will probably serve to make this more clear.

An insulated wire runs from the metallic layers on the roof of the car to switch S, which is shown open in the sketch. When a message is to be received on the car from a station more or less remote, the switch is thrown to the left to connect with a wire running to the telephone receiver, T. The other wire from this receiver is run down to one of the axles and there permanently connected, thus making a ground. The operator puts the receiver to his ear and listens for the message, which the telephone renders audible in the Morse characters.

If a message is to be transmitted from the car to a receiving station, near or distant, the switch, S, is thrown to the other side, thus connecting with a wire leading to one end of the secondary of induction-coil C. The other end of the secondary is connected with the grounding wire. The primary of the induction-coil is connected as shown, one end going to key K and the other to the buzzer circuit. The other side of the key is connected to the transmitting battery, while the opposite pole of this battery is connected in the buzzer circuit. The buzzer, R, is maintained in rapid vibration by its independent auxiliary battery, B<1s>.

When the key is pressed down the circuit is closed, and current from the transmitting battery, B, pa.s.ses through primary of the coil, C, and induces a current of greatly increased potential in the secondary.

The current as it pa.s.ses into the primary, being broken up into short impulses by the tremendously rapid vibrations of the buzzer, induces similarly rapid waves of high potential in the secondary, and these in turn pa.s.s to the roof and thence through the intervening air by induction to the telegraph wire. By a continued lifting and depression of the key in the regular manner, these waves are broken up into long and short periods, and are thus transmitted to the station, via the wire, in Morse characters, dots and dashes.

The receiving stations along the line of the railway were similarly equipped as to apparatus, and, generally speaking the operations of sending and receiving messages were substantially the same as above described.

The equipment of an operator on a car was quite simple consisting merely of a small lap-board, on which were mounted the key, coil, and buzzer, leaving room for telegraph blanks. To this board were also attached flexible conductors having spring clips, by means of which connections could be made quickly with conveniently placed terminals of the ground, roof, and battery wires. The telephone receiver was held on the head with a spring, the flexible connecting wire being attached to the lap board, thus leaving the operator with both hands free.

The system, as shown in the sketch and elucidated by the text, represents the operation of train telegraphy in a simple form, but combining the main essentials of the art as it was successfully and commercially practiced for a number of years after Edison and Gilliland entered the field. They elaborated the system in various ways, making it more complete; but it has not been deemed necessary to enlarge further upon the technical minutiae of the art for the purpose of this work.

XV. KINETOGRAPH AND PROJECTING KINETOSCOPE

ALTHOUGH many of the arts in which Edison has been a pioneer have been enriched by his numerous inventions and patents, which were subsequent to those of a fundamental nature, the (so-called) motion-picture art is an exception, as the following, together with three other additional patents [30] comprise all that he has taken out on this subject: United States Patent No. 589,168, issued August 31, 1897, reissued in two parts--namely, No. 12,037, under date of September 30,1902, and No.

12,192, under date of January 12, 1904. Application filed August 24, 1891.

[Footnote 30: Not 491,993, issued February 21, 1893; No.

493,426, issued March 14, 1893; No. 772,647, issued October 18, 1904.]

There is nothing surprising in this, however, as the possibility of photographing and reproducing actual scenes of animate life are so thoroughly exemplified and rendered practicable by the apparatus and methods disclosed in the patents above cited, that these basic inventions in themselves practically const.i.tute the art--its development proceeding mainly along the line of manufacturing details. That such a view of his work is correct, the highest criterion--commercial expediency--bears witness; for in spite of the fact that the courts have somewhat narrowed the broad claims of Edison's patents by reason of the investigations of earlier experimenters, practically all the immense amount of commercial work that is done in the motion-picture field to-day is accomplished through the use of apparatus and methods licensed under the Edison patents.

The philosophy of this invention having already been described in Chapter XXI, it will be unnecessary to repeat it here. Suffice it to say by way of reminder that it is founded upon the physiological phenomenon known as the persistence of vision, through which a series of sequential photographic pictures of animate motion projected upon a screen in rapid succession will reproduce to the eye all the appearance of the original movements.

Edison's work in this direction comprised the invention not only of a special form of camera for making original photographic exposures from a single point of view with very great rapidity, and of a machine adapted to effect the reproduction of such pictures in somewhat similar manner but also of the conception and invention of a continuous uniform, and evenly s.p.a.ced tape-like film, so absolutely essential for both the above objects.

The mechanism of such a camera, as now used, consists of many parts a.s.sembled in such contiguous proximity to each other that an ill.u.s.tration from an actual machine would not help to clearness of explanation to the general reader. Hence a diagram showing a sectional view of a simple form of such a camera is presented below.

In this diagram, A represents an outer light-tight box containing a lens, C, and the other necessary mechanism for making the photographic exposures, H<1s> and H<2s> being cases for holding reels of film before and after exposure, F the long, tape-like film, G a sprocket whose teeth engage in perforations on the edges of the film, such sprocket being adapted to be revolved with an intermittent or step-by-step movement by hand or by motor, and B a revolving shutter having an opening and connected by gears with G, and arranged to expose the film during the periods of rest. A full view of this shutter is also represented, with its opening, D, in the small ill.u.s.tration to the right.

In practice, the operation would be somewhat as follows, generally speaking: The lens would first be focussed on the animate scene to be photographed. On turning the main shaft of the camera the sprocket, G, is moved intermittently, and its teeth, catching in the holes in the sensitized film, draws it downward, bringing a new portion of its length in front of the lens, the film then remaining stationary for an instant.

In the mean time, through gearing connecting the main shaft with the shutter, the latter is rotated, bringing its opening, D, coincident with the lens, and therefore exposing the film while it is stationary, after which the film again moves forward. So long as the action is continued these movements are repeated, resulting in a succession of enormously rapid exposures upon the film during its progress from reel H<1s> to its automatic rewinding on reel H<2s>. While the film is pa.s.sing through the various parts of the machine it is guided and kept straight by various sets of rollers between which it runs, as indicated in the diagram.

By an ingenious arrangement of the mechanism, the film moves intermittently so that it may have a much longer period of rest than of motion. As in practice the pictures are taken at a rate of twenty or more per second, it will be quite obvious that each period of rest is infinitesimally brief, being generally one-thirtieth of a second or less. Still it is sufficient to bring the film to a momentary condition of complete rest, and to allow for a maximum time of exposure, comparatively speaking, thus providing means for taking clearly defined pictures. The negatives so obtained are developed in the regular way, and the positive prints subsequently made from them are used for reproduction.

The reproducing machine, or, as it is called in practice, the Projecting Kinetoscope, is quite similar so far as its general operations in handling the film are concerned. In appearance it is somewhat different; indeed, it is in two parts, the one containing the lighting arrangements and condensing lens, and the other embracing the mechanism and objective lens. The "taking" camera must have its parts enclosed in a light-tight box, because of the undeveloped, sensitized film, but the projecting kinetoscope, using only a fully developed positive film, may, and, for purposes of convenient operation, must be accessibly open. The ill.u.s.tration (Fig. 2) will show the projecting apparatus as used in practice.