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many parts assembled in such contiguous proximity to each other that an illustration 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 illustration 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 passing 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 illustration (Fig. 2) will show the projecting apparatus as used in practice.

The philosophy of reproduction is very simple, and is illustrated diagrammatically in Fig. 3, reference letters being the same as in Fig. 1. As to the additional reference letters, I is a condenser J the source of light, and K a reflector.

The positive film is moved intermittently but swiftly throughout its length between the objective lens and a beam of light coming through the condenser, being exposed by the shutter during the periods of rest. This results in a pro- jection of the photographs upon a screen in such rapid succession as to present an apparently continuous photograph of the successive positions of the moving objects, which, therefore, appear to the human eye to be in motion.

The first claim of Reissue Patent No. 12,192 describes the film. It reads as follows:

“An unbroken transparent or translucent tape-like photographic film having thereon uniform, sharply defined, equidistant photographs of successive positions of an object in motion as observed from a single point of view at rapidly recurring intervals of time, such photographs being arranged in a continuous straight-line sequence, unlimited in number save by the length of the film, and sufficient in number to represent the movements of the object throughout an extended period of time.”

XVI

EDISON’S ORE-MILLING INVENTIONS

THE wide range of Edison’s activities in this department of the arts is well represented in the diversity of the numerous patents that have been issued to him from time to time. These patents are between fifty and sixty in number, and include magnetic ore separators of ten distinct types; also breaking, crushing, and grinding
rolls, conveyors, dust-proof bearings, screens, driers, mixers, bricking
apparatus and machines, ovens,
and processes of various kinds.

A description of the many devices
in each of these divisions
would require more space than is
available; hence, we shall confine
ourselves to a few items of predominating importance, already referred
to in the narrative. commencing
with the fundamental magnetic ore
separator, which was covered by
United States Patent No. 228,329,
issued June 1, 1880.

The illustration here presented is copied from the drawing forming part of this patent. A hopper with adjustable feed is supported several feet above a bin having a central partition. Almost midway between the hopper and the bin is placed an electromagnet whose polar extension is so arranged as to be a little to one side of a stream of material falling from the hopper. Normally, a stream of finely divided ore falling from the hopper would fall into that portion of the bin lying to the left of the partition. If, however, the magnet is energized from a source of current, the magnetic particles in the falling stream are attracted by and move toward the magnet, which is so placed with relation to the falling material that the magnetic particles cannot be attracted entirely to the magnet before gravity has carried them past. Hence, their trajectory is altered, and they fall on the right-hand side of the partition in the bin, while the non-magnetic portion of the stream continues in a straight line and falls on the other side, thus effecting a complete separation.

This simple but effective principle was the one employed by Edison in his great concentrating plant already described. In practice, the numerous hoppers, magnets, and bins were many feet in length; and they were arranged in batteries of varied magnetic strength, in order that the intermingled mass of crushed rock and iron ore might be more thoroughly separated by being passed through magnetic fields of successively increasing degrees of attracting power. Altogether there were about four hundred and eighty of these immense magnets in the plant, distributed in various buildings in batteries as above mentioned, the crushed rock containing the iron ore being delivered to them by conveyors, and the gangue and ore being taken away after separation by two other conveyors and delivered elsewhere. The magnetic separators at first used by Edison at this plant were of the same generality as the ones employed some years previously in the separation of sea-shore sand, but greatly enlarged and improved. The varied experiences gained in the concentration of vast quantities of ore led naturally to a greater development, and several new types and arrangements of magnetic separators were evolved and elaborated by him from first to last, during the progress of the work at the concentrating plant.

The magnetic separation of iron from its ore being the foundation idea of the inventions now under discussion, a consideration of the separator has naturally taken precedence over those of collateral but inseparable interest. The ore- bearing rock, however, must first be ground to powder before it can be separated; hence, we will now begin at the root of this operation and consider the “giant rolls,” which Edison devised for breaking huge masses of rock. In his application for United States Patent No. 672,616, issued April 23, 1901, applied for on July 16, 1897, he says: “The object of my invention is to produce a method for the breaking of rock which will be simple and effective, will not require the hand-sledging or blasting of the rock down to pieces of moderate size, and will involve the consumption of a small amount of power.”

While this quotation refers to the method as “simple,” the patent under consideration covers one of the most bold and daring projects that Edison has ever evolved. He proposed to eliminate the slow and expensive method of breaking large boulders manually, and to substitute therefor momentum and kinetic energy applied through the medium of massive machinery, which, in a few seconds, would break into small pieces a rock as big as an ordinary upright cottage piano, and weighing as much as six tons. Engineers to whom Edison communicated his ideas were unanimous in declaring the thing an impossibility; it was like driving two express-trains into each other at full speed to crack a great rock placed between them; that no practical machinery could be built to stand the terrific impact and strains. Edison’s convictions were strong, however, and he persisted. The experiments were of heroic size, physically and financially, but after a struggle of several years and an expenditure of about $100,000, he realized the correctness and practicability of his plans in the success of the giant rolls, which were the outcome of his labors.

The giant rolls consist of a pair of iron cylinders of massive size and weight, with removable wearing plates having irregular surfaces formed by projecting knobs. These rolls are mounted side by side in a very heavy frame (leaving a gap of about fourteen inches between them), and are so belted up with the source of power that they run in opposite directions. The giant rolls described by Edison in the above- named patent as having been built and operated by him had a combined weight of 167,000 pounds, including all moving parts, which of themselves weighed about seventy tons, each roll being six feet in diameter and five feet long. A top view of the rolls is shown in the sketch, one roll and one of its bearings being shown in section.

In Fig. 2 the rolls are illustrated diagrammatically. As a sketch of this nature, even if given with a definite scale, does not always carry an adequate idea of relative dimensions to a non-technical reader, we present in Fig. 3 a perspective illustration of the giant rolls as installed in the concentrating plant.

In practice, a small amount of power is applied to run the giant rolls gradually up to a surface speed of several thousand feet a minute. When this high speed is attained, masses of rock weighing several tons in one or more pieces are dumped into a hopper which guides them into the gap between the rapidly revolving rolls. The effect is to partially arrest the swift motion of the rolls instantaneously, and thereby develop and expend an enormous amount of kinetic energy, which with pile-driver effect cracks the rocks and breaks them into pieces small enough to pass through the fourteen- inch gap. As the power is applied to the rolls through slipping friction-clutches, the speed of the driving-pulleys is not materially reduced; hence the rolls may again be quickly speeded up to their highest velocity while another load of rock is being hoisted in position to be dumped into the hopper. It will be obvious from the foregoing that if it were attempted to supply the great energy necessary for this operation by direct application of steam-power, an engine of enormous horse-power would be required, and even then it is doubtful if one could be constructed of sufficient strength to withstand the terrific strains that would ensue. But the work is done by the great momentum and kinetic energy obtained by speeding up these tremendous masses of metal, and then suddenly opposing their progress, the engine being relieved of all strain through the medium of the slipping friction-clutches. Thus, this cyclopean operation may be continuously conducted with an amount of power prodigiously inferior, in proportion, to the results accomplished.

The sketch (Fig. 4) showing a large boulder being dumped into the hopper, or roll-pit, will serve to illustrate the method of feeding these great masses of rock to the rolls, and will also enable the reader to form an idea of the rapidity of the breaking operation, when it is stated that a boulder of the size represented would be reduced by the giant rolls to pieces a trifle larger than a man’s head in a few seconds.

After leaving the giant rolls the broken rock passed on through other crushing-rolls of somewhat similar construc- tion. These also were invented by Edison, but antedated those previously described; being covered by Patent No. 567,187, issued September 8, 1896. These rolls were intended for the reducing of “one-man-size” rocks to small pieces, which at the time of their original inception was about the standard size of similar machines. At the Edison concentrating plant the broken rock, after passing through these rolls, was further reduced in size by other rolls, and was then ready to be crushed to a fine powder through the medium of another remarkable machine devised by

NOTE.–Figs. 3 and 4 are reproduced from similar sketches on pages 84 and 85 of McClure’s Magazine for November, 1897, by permission of S. S. McClure Co.

Edison to meet his ever-recurring and well-defined ideas of the utmost economy and efficiency. The best fine grinding- machines that it was then possible to obtain were so inefficient as to involve a loss of 82 per cent. of the power applied. The thought of such an enormous loss was unbearable, and he did not rest until he had invented and put into use an entirely new grinding-machine, which was called the “three-high” rolls. The device was covered by a patent issued to him on November 21, 1899, No. 637,327. It was a most noteworthy invention, for it brought into the art not only a greater efficiency of grinding than had ever been dreamed of before, but also a tremendous economy by the saving of power; for whereas the previous efficiency had been 18 per cent. and the loss 82 per cent., Edison reversed these figures, and in his three-high rolls produced a working efficiency of 84 per cent., thus reducing the loss of power by friction to 16 per cent. A diagrammatic sketch of this remarkable machine is shown in Fig. 5, which shows a front elevation with the casings, hopper, etc., removed, and also shows above the rolls the rope and pulleys, the supports for which are also removed for the sake of clearness in the illustration.

For the convenience of the reader, in referring to Fig. 5, we will repeat the description of the three-high rolls, which is given on pages 487 and 488 of the preceding narrative.

In the two end-pieces of a heavy iron frame were set three rolls, or cylinders–one in the centre, another below, and the other above–all three being in a vertical line. These rolls were about three feet in diameter, made of cast-iron, and had face-plates of chilled-iron.[31] The lowest roll was set in a fixed bearing at the bottom of the frame, and, therefore, could only turn around on its axis. The middle and top rolls were free to move up or down from and toward the lower roll, and the shafts of the middle and upper rolls were set in a loose bearing which could slip up and down in the iron frame. It will be apparent, therefore, that any material which passed in between the top and the middle rolls, and the middle and bottom rolls, could be ground as fine as might be desired, depending entirely upon the amount of pressure applied to the loose rolls. In operation the material passed first through the upper and middle rolls, and then between the middle and lowest rolls.

[31] The faces of these rolls were smooth, but as three-high rolls came into use later in Edison’s Portland cement operations the faces were corrugated so as to fit into each other, gear-fashion, to provide for a high rate of feed.

This pressure was applied in a most ingenious manner. On the ends of the shafts of the bottom and top rolls there were cylindrical sleeves, or bearings, having seven sheaves in which was run a half-inch endless wire rope. This rope was wound seven times over the sheaves as above, and led upward and over a single-groove sheave, which was operated by the piston of an air-cylinder, and in this manner the pressure was applied to the rolls. It will be seen, therefore that the system consisted in a single rope passed over sheaves and so arranged that it could be varied in length, thus providing for elasticity in exerting pressure and regulating it as desired. The efficiency of this system was incomparably greater than that of any other known crusher or grinder, for while a pressure of one hundred and twenty-five thousand pounds could be exerted by these rolls, friction was almost entirely eliminated, because the upper and lower roll bearings turned with the rolls and revolved in the wire rope, which constituted the bearing proper.

Several other important patents have been issued to Edison for crushing and grinding rolls, some of them being for elaborations and improvements of those above described but all covering methods of greater economy and effectiveness in rock-grinding.

Edison’s work on conveyors during the period of his ore- concentrating labors was distinctively original, ingenious and far in advance of the times. His conception of the concentrating problem was broad and embraced an entire system, of which a principal item was the continuous transfer of enormous quantities of material from place to place at the lowest possible cost. As he contemplated the concentration of six thousand tons daily, the expense of manual labor to move such an immense quantity of rock, sand, and ore would be absolutely prohibitive. Hence, it became necessary to invent a system of conveyors that would be capable of transferring this mass of material from one place to another. And not only must these conveyors be capable of carrying the material, but they must also be devised so that they would automatically receive and discharge their respective loads at appointed places. Edison’s ingenuity, engineering ability, and inventive skill were equal to the task, however, and were displayed in a system and variety of conveyors that in practice seemed to act with almost human discrimination. When fully installed throughout the plant, they automatically transferred daily a mass of material equal to about one hundred thousand cubic feet, from mill to mill, covering about a mile in the transit. Up and down, winding in and out, turning corners, delivering material from one to another, making a number of loops in the drying-oven, filling up bins and passing on to the next when they were full, these conveyors in automatic action seemingly played their part with human intelligence, which was in reality the reflection of the intelligence and ingenuity that had originally devised them and set them in motion.

Six of Edison’s patents on conveyors include a variety of devices that have since came into broad general use for similar work, and have been the means of effecting great economies in numerous industries of widely varying kinds. Interesting as they are, however, we shall not attempt to describe them in detail, as the space required would be too great. They are specified in the list of patents following this Appendix, and may be examined in detail by any interested student.

In the same list will also be found a large number of Edison’s patents on apparatus and methods of screening, drying, mixing, and briquetting, as well as for dust-proof bearings, and various types and groupings of separators, all of which were called forth by the exigencies and magnitude of his great undertaking, and without which he could not possibly have attained the successful physical results that crowned his labors. Edison’s persistence in reducing the cost of his operations is noteworthy in connection with his screening and drying inventions, in which the utmost advantage is taken of the law of gravitation. With its assistance, which cost nothing, these operations were performed perfectly. It was only necessary to deliver the material at the top of the chambers, and during its natural descent it was screened or dried as the case might be.

All these inventions and devices, as well as those described in detail above (except magnetic separators and mixing and briquetting machines), are being used by him to-day in the manufacture of Portland cement, as that industry presents many of the identical problems which presented themselves in relation to the concentration of iron ore.

XVII

THE LONG CEMENT KILN

IN this remarkable invention, which has brought about a striking innovation in a long-established business, we see another characteristic instance of Edison’s incisive reasoning and boldness of conception carried into practical effect in face of universal opinions to the contrary.

For the information of those unacquainted with the process of manufacturing Portland cement, it may be stated that the material consists preliminarily of an intimate mixture of cement rock and limestone, ground to a very fine powder. This powder is technically known in the trade as “chalk,” and is fed into rotary kilns and “burned”; that is to say, it is subjected to a high degree of heat obtained by the combustion of pulverized coal, which is injected into the interior of the kiln. This combustion effects a chemical decomposition of the chalk, and causes it to assume a plastic consistency and to collect together in the form of small spherical balls. which are known as “clinker.” Kilns are usually arranged with a slight incline, at the upper end of which the chalk is fed in and gradually works its way down to the interior flame of burning fuel at the other end. When it arrives at the lower end, the material has been “burned,” and the clinker drops out into a receiving chamber below. The operation is continuous, a constant supply of chalk passing in at one end of the kiln and a continuous dribble of clinker-balls dropping out at the other. After cooling, the clinker is ground into very fine powder, which is the Portland cement of commerce.

It is self-evident that an ideal kiln would be one that produced the maximum quantity of thoroughly clinkered material with a minimum amount of fuel, labor, and investment. When Edison was preparing to go into the cement business, he looked the ground over thoroughly, and, after considerable investigation and experiment, came to the conclusion that prevailing conditions as to kilns were far from ideal.

The standard kilns then in use were about sixty feet in length, with an internal diameter of about five feet. In all rotary kilns for burning cement, the true clinkering operation takes place only within a limited portion of their total length, where the heat is greatest; hence the interior of the kiln may be considered as being divided longitudinally into two parts or zones–namely, the combustion, or clinkering, zone, and the zone of oncoming raw material. In the sixty- foot kiln the length of the combustion zone was about ten feet, extending from a point six or eight feet from the lower, or discharge, end to a point about eighteen feet from that end. Consequently, beyond that point there was a zone of only about forty feet, through which the heated gases passed and came in contact with the oncoming material, which was in movement down toward the clinkering zone. Since the bulk of oncoming material was small, the gases were not called upon to part with much of their heat, and therefore passed on up the stack at very high temperatures, ranging from 1500 degrees to 1800 degrees Fahr. Obviously, this heat was entirely lost.

An additional loss of efficiency arose from the fact that the material moved so rapidly toward the combustion zone that it had not given up all its carbon dioxide on reaching there; and by the giving off of large quantities of that gas within the combustion zone, perfect and economical combustion of coal could not be effected.

The comparatively short length of the sixty-foot kiln not only limited the amount of material that could be fed into it, but the limitation in length of the combustion zone militated against a thorough clinkering of the material, this operation being one in which the elements of time and proper heat are prime considerations. Thus the quantity of good clinker obtainable was unfavorably affected. By reason of these and other limitations and losses, it had been possible, in practice, to obtain only about two hundred and fifty barrels of clinker per day of twenty-four hours; and that with an expenditure for coal proportionately equal to about 29 to 33 per cent. of the quantity of clinker produced, even assuming that all the clinker was of good quality.

Edison realized that the secret of greater commercial efficiency and improvement of quality lay in the ability to handle larger quantities of material within a given time, and to produce a more perfect product without increasing cost or investment in proportion. His reasoning led him to the conclusion that this result could only be obtained through the use of a kiln of comparatively great length, and his investigations and experiments enabled him to decide upon a length of one hundred and fifty feet, but with an increase in diameter of only six inches to a foot over that of the sixty- foot kiln.

The principal considerations that influenced Edison in making this radical innovation may be briefly stated as follows:

First. The ability to maintain in the kiln a load from five to seven times greater than ordinarily employed, thereby tending to a more economical output.

Second. The combustion of a vastly increased bulk of pulverized coal and a greatly enlarged combustion zone, extending about forty feet longitudinally into the kiln–thus providing an area within which the material might be maintained in a clinkering temperature for a sufficiently long period to insure its being thoroughly clinkered from periphery to centre.

Third. By reason of such a greatly extended length of the zone of oncoming material (and consequently much greater bulk), the gases and other products of combustion would be cooled sufficiently between the combustion zone and the stack so as to leave the kiln at a comparatively low temperature. Besides, the oncoming material would thus be gradually raised in temperature instead of being heated abruptly, as in the shorter kilns.

Fourth. The material having thus been greatly raised in temperature before reaching the combustion zone would have parted with substantially all its carbon dioxide, and therefore would not introduce into the combustion zone sufficient of that gas to disturb the perfect character of the combustion.

Fifth. On account of the great weight of the heavy load in a long kiln, there would result the formation of a continuous plastic coating on that portion of the inner surface of the kiln where temperatures are highest. This would effectively protect the fire-brick lining from the destructive effects of the heat.

Such, in brief, were the essential principles upon which Edison based his conception and invention of the long kiln, which has since become so well known in the cement business.

Many other considerations of a minor and mechanical nature, but which were important factors in his solution of this difficult problem, are worthy of study by those intimately associated with or interested in the art. Not the least of the mechanical questions was settled by Edison’s decision to make this tremendously long kiln in sections of cast-iron, with flanges, bolted together, and supported on rollers rotated by electric motors. Longitudinal expansion and thrust were also important factors to be provided for, as well as special devices to prevent the packing of the mass of material as it passed in and out of the kiln. Special provision was also made for injecting streams of pulverized coal in such manner as to create the largely extended zone of combustion. As to the details of these and many other in- genious devices, we must refer the curious reader to the patents, as it is merely intended in these pages to indicate in a brief manner the main principles of Edison’s notable inventions. The principal United States patent on the long kiln was issued October 24, 1905, No. 802,631.

That his reasonings and deductions were correct in this case have been indubitably proven by some years of experience with the long kiln in its ability to produce from eight hundred to one thousand barrels of good clinker every twenty-four hours, with an expenditure for coal proportionately equal to about only 20 per cent. of the quantity of clinker produced.

To illustrate the long cement kiln by diagram would convey but little to the lay mind, and we therefore present an illustration (Fig. 1) of actual kilns in perspective, from which sense of their proportions may be gathered.

XVIII

EDISON’S NEW STORAGE BATTERY

GENERICALLY considered, a “battery” is a device which generates electric current. There are two distinct species of battery, one being known as “primary,” and the other as “storage,” although the latter is sometimes referred to as a “secondary battery” or “accumulator.” Every type of each of these two species is essentially alike in its general make-up; that is to say, every cell of battery of any kind contains at least two elements of different nature immersed in a more or less liquid electrolyte of chemical character. On closing the circuit of a primary battery an electric current is generated by reason of the chemical action which is set up between the electrolyte and the elements. This involves a gradual consumption of one of the elements and a corresponding exhaustion of the active properties of the electrolyte. By reason of this, both the element and the electrolyte that have been used up must be renewed from time to time, in order to obtain a continued supply of electric current.

The storage battery also generates electric current through chemical action, but without involving the constant repriming with active materials to replace those consumed and exhausted as above mentioned. The term “storage,” as applied to this species of battery, is, however, a misnomer, and has been the cause of much misunderstanding to nontechnical persons. To the lay mind a “storage” battery presents itself in the aspect of a device in which electric energy is STORED, just as compressed air is stored or accumulated in a tank. This view, however, is not in accordance with facts. It is exactly like the primary battery in the fundamental circumstance that its ability for generating electric current depends upon chemical action. In strict terminology it is a “reversible” battery, as will be quite obvious if we glance briefly at its philosophy. When a storage battery is “charged,” by having an electric current passed through it, the electric energy produces a chemical effect, adding oxygen to the positive plate, and taking oxygen away from the negative plate. Thus, the positive plate becomes oxidized, and the negative plate reduced. After the charging operation is concluded the battery is ready for use, and upon its circuit being closed through a translating device, such as a lamp or motor, a reversion (“discharge”) takes place, the positive plate giving up its oxygen, and the negative plate being oxidized. These chemical actions result in the generation of an electric current as in a primary battery. As a matter of fact, the chemical actions and reactions in a storage battery are much more complex, but the above will serve to afford the lay reader a rather simple idea of the general result arrived at through the chemical activity referred to.

The storage battery, as a commercial article, was introduced into the market in the year 1881. At that time, and all through the succeeding years, until about 1905, there was only one type that was recognized as commercially practicable–namely, that known as the lead-sulphuric-acid cell, consisting of lead plates immersed in an electrolyte of dilute sulphuric acid. In the year last named Edison first brought out his new form of nickel-iron cell with alkaline electrolyte, as we have related in the preceding narrative. Early in the eighties, at Menlo Park, he had given much thought to the lead type of storage battery, and during the course of three years had made a prodigious number of experiments in the direction of improving it, probably performing more experiments in that time than the aggregate of those of all other investigators. Even in those early days he arrived at the conclusion that the lead-sulphuric-acid combination was intrinsically wrong, and did not embrace the elements of a permanent commercial device. He did not at that time, however, engage in a serious search for another form of storage battery, being tremendously occupied with his lighting system and other matters.

It may here be noted, for the information of the lay reader, that the lead-acid type of storage battery consists of two or more lead plates immersed in dilute sulphuric acid and contained in a receptacle of glass, hard rubber, or other special material not acted upon by acid. The plates are prepared and “formed” in various ways, and the chemical actions are similar to those above stated, the positive plate being oxidized and the negative reduced during “charge,” and reversed during “discharge.” This type of cell, however, has many serious disadvantages inherent to its very nature. We will name a few of them briefly. Constant dropping of fine particles of active material often causes short-circuiting of the plates, and always necessitates occasional washing out of cells; deterioration through “sulphation” if discharge is continued too far or if recharging is not commenced quickly enough; destruction of adjacent metal- work by the corrosive fumes given out during charge and discharge; the tendency of lead plates to “buckle” under certain conditions; the limitation to the use of glass, hard rubber, or similar containers on account of the action of the acid; and the immense weight for electrical capacity. The tremendously complex nature of the chemical reactions which take place in the lead-acid storage battery also renders it an easy prey to many troublesome diseases.

In the year 1900, when Edison undertook to invent a storage battery, he declared it should be a new type into which neither sulphuric nor any other acid should enter. He said that the intimate and continued companionship of an acid and a metal was unnatural, and incompatible with the idea of durability and simplicity. He furthermore stated that lead was an unmechanical metal for a battery, being heavy and lacking stability and elasticity, and that as most metals were unaffected by alkaline solutions, he was going to experiment in that direction. The soundness of his reasoning is amply justified by the perfection of results obtained in the new type of storage battery bearing his name, and now to be described.

The essential technical details of this battery are fully described in an article written by one of Edison’s laboratory staff, Walter E. Holland, who for many years has been closely identified with the inventor’s work on this cell The article was published in the Electrical World, New York, April 28, 1910; and the following extracts there- from will afford an intelligent comprehension of this invention:

“The `A’ type Edison cell is the outcome of nine years of costly experimentation and persistent toil on the part of its inventor and his associates….

“The Edison invention involves the use of an entirely new voltaic combination in an alkaline electrolyte, in place of the lead-lead-peroxide combination and acid electrolyte, characteristic of all other commercial storage batteries. Experience has proven that this not only secures durability and greater output per unit-weight of battery, but in addition there is eliminated a long list of troubles and diseases inherent in the lead-acid combination….

“The principle on which the action of this new battery is based is the oxidation and reduction of metals in an electrolyte which does not combine with, and will not dissolve, either the metals or their oxides; and an electrolyte, furthermore, which, although decomposed by the action of the battery, is immediately re-formed in equal quantity; and therefore in effect is a CONSTANT element, not changing in density or in conductivity.

“A battery embodying this basic principle will have features of great value where lightness and durability are desiderata. For instance, the electrolyte, being a constant factor, as explained, is not required in any fixed and large amount, as is the case with sulphuric acid in the lead battery; thus the cell may be designed with minimum distancing of plates and with the greatest economy of space that is consistent with safe insulation and good mechanical design. Again, the active materials of the electrodes being insoluble in, and absolutely unaffected by, the electrolyte, are not liable to any sort of chemical deterioration by action of the electrolyte–no matter how long continued….

“The electrolyte of the Edison battery is a 21 per cent.

solution of potassium hydrate having, in addition, a small amount of lithium hydrate. The active metals of the electrodes –which will oxidize and reduce in this electrolyte without dissolution or chemical deterioration–are nickel and iron. These active elements are not put in the plates AS METALS; but one, nickel, in the form of a hydrate, and the other, iron, as an oxide.

“The containing cases of both kinds of active material (Fig. 1), and their supporting grids (Fig. 2), as well as the bolts, washers, and nuts used in assembling (Fig. 3), and even the retaining can and its cover (Fig. 4), are all made of nickel-plated steel–a material in which lightness, durability and mechanical strength are most happily combined, and a material beyond suspicion as to corrosion in an alkaline electrolyte….

“An essential part of Edison’s discovery of active ma- setials for an alkaline storage battery was the PREPARATION of these materials. Metallic powder of iron and nickel, or even oxides of these metals, prepared in the ordinary way, are not chemically active in a sufficient degree to work in a battery. It is only when specially prepared iron oxide of exceeding fineness, and nickel hydrate conforming to certain physical, as well as chemical, standards can be made that the alkaline battery is practicable. Needless to say, the working out of the conditions and processes of manufacture of the materials has involved great ingenuity and endless experimentation.”

The article then treats of Edison’s investigations into means for supporting and making electrical connection with the active materials, showing some of the difficulties encountered and the various discoveries made in developing the perfected cell, after which the writer continues his description of the “A” type cell, as follows:

“It will be seen at once that the construction of the two kinds of plate is radically different. The negative or iron plate (Fig. 5) has the familiar flat-pocket construction. Each negative contains twenty-four pockets–a pocket being 1/2 inch wide by 3 inches long, and having a maximum thickness of a little more than 1/8 inch. The positive or nickel plate (Fig. 6) is seen to consist of two rows of round rods or pencils, thirty in number, held in a vertical position by a steel support-frame. The pencils have flat flanges at the ends (formed by closing in the metal case), by which they are supported and electrical connection is made. The frame is slit at the inner horizontal edges, and then folded in such a way as to make individual clamping-jaws for each end- flange. The clamping-in is done at great pressure, and the resultant plate has great rigidity and strength.

“The perforated tubes into which the nickel active material is loaded are made of nickel-plated steel of high quality. They are put together with a double-lapped spiral seam to give expansion-resisting qualities, and as an additional precaution small metal rings are slipped on the outside. Each tube is 1/4 inch in diameter by 4 1/8 inches long, add has eight of the reinforcing rings.

“It will be seen that the `A’ positive plate has been given the theoretically best design to prevent expansion and overcome trouble from that cause. Actual tests, long continued under very severe conditions, have shown that the construction is right, and fulfils the most sanguine expectations.”

Mr. Holland in his article then goes on to explain the development of the nickel flakes as the conducting factor in the positive element, but as this has already been described in Chapter XXII, we shall pass on to a later point, where he says:

“An idea of the conditions inside a loaded tube can best be had by microscopic examination. Fig. 7 shows a magnified section of a regularly loaded tube which has been sawed lengthwise. The vertical bounding walls are edges of the perforated metal containing tube; the dark horizontal lines are layers of nickel flake, while the light-colored thicker layers represent the nickel hydrate. It should be noted that the layers of flake nickel extend practically unbroken across the tube and make contact with the metal wall at both sides. These metal layers conduct current to or from the active nickel hydrate in all parts of the tube very efficiently. There are about three hundred and fifty layers of each kind of material in a 4 1/8 -inch tube, each layer of nickel hydrate being about 0.01 inch thick; so it will be seen that the current does not have to penetrate very far into the nickel hydrate–one-half a layer’s thickness being the maximum distance. The perforations of the containing tube, through which the electrolyte reaches the active material, are also shown in Fig. 7.”

In conclusion, the article enumerates the chief characteristics of the Edison storage battery which fit it pre- eminently for transportation service, as follows: 1. No loss of active material, hence no sediment short-circuits. 2. No jar breakage. 3. Possibility of quick disconnection or replacement of any cell without employment of skilled labor. 4. Impossibility of “buckling” and harmlessness of a dead short-circuit. 5. Simplicity of care required. 6. Durability of materials and construction. 7. Impossibility of “sulphation.” 8. Entire absence of corrosive fumes. 9. Commercial advantages of light weight. 10. Duration on account of its dependability. 11. Its high practical efficiency.

XIX

EDISON’S POURED CEMENT HOUSE

THE inventions that have been thus far described fall into two classes–first, those that were fundamental in the great arts and industries which have been founded and established upon them, and, second, those that have entered into and enlarged other arts that were previously in existence. On coming to consider the subject now under discussion, however, we find ourselves, at this writing, on the threshold of an entirely new and undeveloped art of such boundless possibilities that its ultimate extent can only be a matter of conjecture.

Edison’s concrete house, however, involves two main considerations, first of which was the conception or creation of the IDEA–vast and comprehensive–of providing imperishable and sanitary homes for the wage-earner by molding an entire house in one piece in a single operation, so to speak, and so simply that extensive groups of such dwellings could be constructed rapidly and at very reasonable cost. With this idea suggested, one might suppose that it would be a simple matter to make molds and pour in a concrete mixture. Not so, however. And here the second consideration presents itself. An ordinary cement mixture is composed of crushed stone, sand, cement, and water. If such a mixture be poured into deep molds the heavy stone and sand settle to the bottom. Should the mixture be poured into a horizontal mold, like the floor of a house, the stone and sand settle, forming an ununiform mass. It was at this point that invention commenced, in order to produce a concrete mixture which would overcome this crucial difficulty. Edison, with characteristic thoroughness, took up a line of investigation, and after a prolonged series of experiments succeeded in inventing a mixture that upon hardening re- mained uniform throughout its mass. In the beginning of his experimentation he had made the conditions of test very severe by the construction of forms similar to that shown in the sketch below.

This consisted of a hollow wooden form of the dimensions indicated. The mixture was to be poured into the hopper until the entire form was filled, such mixture flowing down and along the horizontal legs and up the vertical members. It was to be left until the mixture was hard, and the requirement of the test was that there should be absolute uniformity of mixture and mass throughout. This was finally accomplished, and further invention then proceeded along engineering lines looking toward the devising of a system of molds with which practicable dwellings might be cast.

Edison’s boldness and breadth of conception are well illustrated in his idea of a poured house, in which he displays his accustomed tendency to reverse accepted methods. In fact, it is this very reversal of usual procedure that renders it difficult for the average mind to instantly grasp the full significance of the principles involved and the results attained.

Up to this time we have been accustomed to see the erection of a house begun at the foundation and built up slowly, piece by piece, of solid materials: first the outer frame, then the floors and inner walls, followed by the stairways, and so on up to the putting on of the roof. Hence, it requires a complete rearrangement of mental conceptions to appreciate Edison’s proposal to build a house FROM THE TOP DOWNWARD, in a few hours, with a freely flowing material poured into molds, and in a few days to take away the molds and find a complete indestructible sanitary house, including foundation, frame, floors, walls, stairways, chimneys, sanitary arrangements, and roof, with artistic ornamentation inside and out, all in one solid piece, as if it were graven or bored out of a rock.

To bring about the accomplishment of a project so extraordinarily broad involves engineering and mechanical conceptions of a high order, and, as we have seen, these have been brought to bear on the subject by Edison, together with an intimate knowledge of compounded materials.

The main features of this invention are easily comprehensible with the aid of the following diagrammatic sectional sketch:

It should be first understood that the above sketch is in broad outline, without elaboration, merely to illustrate the working principle; and while the upright structure on the right is intended to represent a set of molds in position to form a three-story house, with cellar, no regular details of such a building (such as windows, doors, stairways, etc.) are here shown, as they would only tend to complicate an explanation.

It will be noted that there are really two sets of molds, an inside and an outside set, leaving a space between them throughout. Although not shown in the sketch, there is in practice a number of bolts passing through these two sets of molds at various places to hold them together in their relative positions. In the open space between the molds there are placed steel rods for the purpose of reinforcement; while all through the entire structure provision is made for water and steam pipes, gas-pipes and electric-light wires being placed in appropriate positions as the molds are assembled.

At the centre of the roof there will be noted a funnel- shaped opening. Into this there is delivered by the endless chain of buckets shown on the left a continuous stream of a special free-flowing concrete mixture. This mixture descends by gravity, and gradually fills the entire space between the two sets of molds. The delivery of the material–or “pouring,” as it is called–is continued until every part of the space is filled and the mixture is even with the tip of the roof, thus completing the pouring, or casting, of the house. In a few days afterward the concrete will have hardened sufficiently to allow the molds to be taken away leaving an entire house, from cellar floor to the peak of the roof, complete in all its parts, even to mantels and picture molding, and requiring only windows and doors, plumbing, heating, and lighting fixtures to make it ready for habitation.

In the above sketch the concrete mixers, A, B, are driven by the electric motor, C. As the material is mixed it descends into the tank, D, and flows through a trough into a lower tank, E, in which it is constantly stirred, and from which it is taken by the endless chain of buckets and dumped into the funnel-shaped opening at the top of the molds, as above described.

The molds are made of cast-iron in sections of such size and weight as will be most convenient for handling, mostly in pieces not exceeding two by four feet in rectangular dimensions. The subjoined sketch shows an exterior view of several of these molds as they appear when bolted together, the intersecting central portions representing ribs, which are included as part of the casting for purposes of strength and rigidity.

The molds represented above are those for straight work, such as walls and floors. Those intended for stairways, eaves, cornices, windows, doorways, etc., are much more complicated in design, although the same general principles are employed in their construction.

While the philosophy of pouring or casting a complete house in its entirety is apparently quite simple, the development of the engineering and mechanical questions involves the solution of a vast number of most intricate and complicated problems covering not only the building as a whole, but its numerous parts, down to the minutest detail. Safety, convenience, duration, and the practical impossibility of altering a one-piece solid dwelling are questions that must be met before its construction, and therefore Edison has proceeded calmly on his way toward the goal he has ever had clearly in mind, with utter indifference to the criticisms and jeers of those who, as “experts,” have professed positive knowledge of the impossibility of his carrying out this daring scheme.

LIST OF UNITED STATES PATENTS

List of United States patents granted to Thomas A. Edison, arranged according to dates of execution of applications for such patents. This list shows the inventions as Mr. Edison has worked
upon them from year to year

1868

NO. TITLE OF PATENT DATE EXECUTED DATE EXECUTED 90,646, Electrographic Vote Recorder . . . . .Oct. 13, 1868

1869

91,527 Printing Telegraph (reissued October 25, 1870, numbered 4166, and August 5, 1873, numbered 5519). . . . . . . .Jan. 25, 1869 96,567 Apparatus for Printing Telegraph (reissued February 1, 1870, numbered
3820). . . . . . . . . . . . . . . . .Aug. 17, 1869 96,681 Electrical Switch for Telegraph ApparatusAug. 27, 1869 102,320 Printing Telegraph–Pope and Edison (reissued April 17, 1877, numbered 7621, and December 9, 1884, numbered 10,542). . . . . . . . . . . . . . . Sept. 16, 1869 103,924 Printing Telegraphs–Pope and Edison (reissued August 5, 1873)

1870

103,035 Electromotor Escapement. . . . . . . . Feb. 5, 1870 128,608 Printing Telegraph Instruments . . . . .May 4, 1870 114,656 Telegraph Transmitting Instruments . .June 22, 1870 114,658 Electro Magnets for Telegraph
Instruments. . . . . . . . . . . . . .June 22, 1870 114,657 Relay Magnets for Telegraph
Instruments. . . . . . . . . . . . . .Sept. 6, 1870 111,112 Electric Motor Governors . . . . . . .June 29, 1870 113,033 Printing Telegraph Apparatus . . . . .Nov. 17, 1870

1871

113,034 Printing Telegraph Apparatus . . . . .Jan. 10, 1871 123,005 Telegraph Apparatus. . . . . . . . . .July 26, 1871 123,006 Printing Telegraph . . . . . . . . . .July 26, 1871 123,984 Telegraph Apparatus. . . . . . . . . .July 26, 1871 124,800 Telegraphic Recording Instruments. . .Aug. 12, 1871 121,601 Machinery for Perforating Paper for Telegraph Purposes . . . . . . . . . .Aug. 16, 1871 126,535 Printing Telegraphs. . . . . . . . . .Nov. 13, 1871 133,841 Typewriting Machine. . . . . . . . . .Nov. 13, 1871

1872
126,532 Printing Telegraphs. . . . . . . . . . .Jan. 3 1872 126,531 Printing Telegraphs. . . . . . . . . .Jan. 17, 1872 126,534 Printing Telegraphs. . . . . . . . . .Jan. 17, 1872 126,528 Type Wheels for Printing Telegraphs. .Jan. 23, 1872 126,529 Type Wheels for Printing Telegraphs. .Jan. 23, 1872 126,530 Printing Telegraphs. . . . . . . . . .Feb. 14, 1872 126,533 Printing Telegraphs. . . . . . . . . .Feb. 14, 1872 132,456 Apparatus for Perforating Paper for Telegraphic Use. . . . . . . . . . . March 15, 1872 132,455 Improvement in Paper for Chemical Telegraphs . . . . . . . . . . . . . April 10, 1872 133,019 Electrical Printing Machine. . . . . April 18, 1872 128,131 Printing Telegraphs. . . . . . . . . April 26, 1872 128,604 Printing Telegraphs. . . . . . . . . April 26, 1872 128,605 Printing Telegraphs. . . . . . . . . April 26, 1872 128,606 Printing Telegraphs. . . . . . . . . April 26, 1872 128,607 Printing Telegraphs. . . . . . . . . April 26, 1872 131,334 Rheotomes or Circuit Directors . . . . .May 6, 1872 134,867 Automatic Telegraph Instruments. . . . .May 8, 1872 134,868 Electro Magnetic Adjusters . . . . . . .May 8, 1872 130,795 Electro Magnets. . . . . . . . . . . . .May 9, 1872 131,342 Printing Telegraphs. . . . . . . . . . .May 9, 1872 131,341 Printing Telegraphs. . . . . . . . . . May 28, 1872 131,337 Printing Telegraphs. . . . . . . . . .June 10, 1872 131,340 Printing Telegraphs. . . . . . . . . .June 10, 1872 131,343 Transmitters and Circuits for Printing Telegraph. . . . . . . . . . . . . . .June 10, 1872 131,335 Printing Telegraphs. . . . . . . . . .June 15, 1872 131,336 Printing Telegraphs. . . . . . . . . .June 15, 1872 131,338 Printing Telegraphs. . . . . . . . . .June 29, 1872 131,339 Printing Telegraphs. . . . . . . . . .June 29, 1872 131,344 Unison Stops for Printing Telegraphs .June 29, 1872 134,866 Printing and Telegraph Instruments . .Oct. 16, 1872 138,869 Printing Telegraphs. . . . . . . . . .Oct. 16, 1872 142,999 Galvanic Batteries . . . . . . . . . .Oct. 31, 1872 141,772 Automatic or Chemical Telegraphs . . . Nov. 5, 1872 135,531 Circuits for Chemical Telegraphs . . . Nov. 9, 1872 146,812 Telegraph Signal Boxes . . . . . . . .Nov. 26, 1872 141,773 Circuits for Automatic Telegraphs. . .Dec. 12, 1872 141,776 Circuits for Automatic Telegraphs. . .Dec. 12, 1872 150,848 Chemical or Automatic Telegraphs . . .Dec. 12, 1872

1873

139,128 Printing Telegraphs. . . . . . . . . .Jan. 21, 1873 139,129 Printing Telegraphs. . . . . . . . . .Feb. 13, 1873 140,487 Printing Telegraphs. . . . . . . . . .Feb. 13, 1873 140,489 Printing Telegraphs. . . . . . . . . .Feb. 13, 1873 138,870 Printing Telegraphs. . . . . . . . . .March 7, 1873 141,774 Chemical Telegraphs. . . . . . . . . .March 7, 1873 141,775 Perforator for Automatic Telegraphs. .March 7, 1873 141,777 Relay Magnets. . . . . . . . . . . . .March 7, 1873 142,688 Electric Regulators for Transmitting Instruments . . . . . . . . . . . . . .March 7, 1873 156,843 Duplex Chemical Telegraphs . . . . . .March 7, 1873 147,312 Perforators for Automatic Telegraphy March 24, 1873 147,314 Circuits for Chemical Telegraphs . . March 24, 1873 150,847 Receiving Instruments for Chemical Telegraphs . . . . . . . . . . . . . March 24, 1873 140,488 Printing Telegraphs. . . . . . . . . April 23, 1873 147,311 Electric Telegraphs. . . . . . . . . April 23, 1873 147,313 Chemical Telegraphs. . . . . . . . . April 23, 1873 147,917 Duplex Telegraphs. . . . . . . . . . April 23, 1873 150,846 Telegraph Relays . . . . . . . . . . April 23, 1873 160,405 Adjustable Electro Magnets for Relays, etc. . . . . . . . . . . . . April 23, 1873 162,633 Duplex Telegraphs. . . . . . . . . . April 22, 1873 151,209 Automatic Telegraphy and Perforators Therefor . . . . . . . . . . . . . . .Aug. 25, 1873 160,402 Solutions for Chemical Telegraph PaperSept. 29, 1873 160,404 Solutions for Chemical Telegraph PaperSept. 29, 1873 160,580 Solutions for Chemical Telegraph PaperOct. 14, 1873 160,403 Solutions for Chemical Telegraph PaperOct. 29, 1873

1874

154,788 District Telegraph Signal Box. . . . .April 2, 1874 168,004 Printing Telegraph . . . . . . . . . . May 22, 1874 166,859 Chemical Telegraphy. . . . . . . . . . June 1, 1874 166,860 Chemical Telegraphy. . . . . . . . . . June 1, 1874 166,861 Chemical Telegraphy. . . . . . . . . . June 1, 1874 158,787 Telegraph Apparatus. . . . . . . . . . Aug. 7, 1874 172,305 Automatic Roman Character
Telegraph. . . . . . . . . . . . . . . Aug. 7, 1874 173,718 Automatic Telegraphy . . . . . . . . . Aug. 7, 1874 178,221 Duplex Telegraphs. . . . . . . . Aug. 19, 1874 178,222 Duplex Telegraphs. . . . . . . . . . .Aug. 19, 1874 178,223 Duplex Telegraphs. . . . . . . . . . .Aug. 19, 1874 180,858 Duplex Telegraphs. . . . . . . . . . .Aug. 19, 1874 207,723 Duplex Telegraphs. . . . . . . . . . .Aug. 19, 1874 480,567 Duplex Telegraphs. . . . . . . . . . .Aug. 19, 1874 207,724 Duplex Telegraphs. . . . . . . . . . .Dec. 14, 1874

1875

168,242 Transmitter and Receiver for Automatic Telegraph. . . . . . . . . . . . . . .Jan. 18, 1875 168,243 Automatic Telegraphs . . . . . . . . .Jan. 18, 1875 168,385 Duplex Telegraphs. . . . . . . . . . .Jan. 18, 1875 168,466 Solution for Chemical Telegraphs . . .Jan. 18, 1875 168,467 Recording Point for Chemical TelegraphJan. 18, 1875 195,751 Automatic Telegraphs . . . . . . . . . Jan. 18 1875 195,752 Automatic Telegraphs . . . . . . . . .Jan. 19, 1875 171,273 Telegraph Apparatus. . . . . . . . . . Feb 11, 1875 169,972 Electric Signalling Instrument . . . . Feb 24, 1875 209,241 Quadruplex Telegraph Repeaters (reissued September 23, 1879, numbered
8906). . . . . . . . . . . . . . . . . Feb 24, 1875

1876

180,857 Autographic Printing . . . . . . . . .March 7, 1876 198,088 Telephonic Telegraphs. . . . . . . . .April 3, 1876 198,089 Telephonic or Electro Harmonic Telegraphs . . . . . . . . . . . . . .April 3, 1876 182,996 Acoustic Telegraphs. . . . . . . . . . .May 9, 1876 186,330 Acoustic Electric Telegraphs . . . . . .May 9, 1876 186,548 Telegraph Alarm and Signal Apparatus . .May 9, 1876 198,087 Telephonic Telegraphs. . . . . . . . . .May 9, 1876 185,507 Electro Harmonic Multiplex Telegraph .Aug. 16, 1876 200,993 Acoustic Telegraph . . . . . . . . . .Aug. 26, 1876 235,142 Acoustic Telegraph . . . . . . . . . .Aug. 26, 1876 200,032 Synchronous Movements for Electric Telegraphs . . . . . . . . . . . . . .Oct. 30, 1876 200,994 Automatic Telegraph Perforator and Transmitter. . . . . . . . . . . . . .Oct. 30, 1876

1877
205,370 Pneumatic Stencil Pens . . . . . . . . Feb. 3, 1877 213,554 Automatic Telegraphs . . . . . . . . . Feb. 3, 1877 196,747 Stencil Pens . . . . . . . . . . . . April 18, 1877 203,329 Perforating Pens . . . . . . . . . . April 18, 1877 474,230 Speaking Telegraph . . . . . . . . . April 18, 1877 217,781 Sextuplex Telegraph. . . . . . . . . . .May 8, 1877 230,621 Addressing Machine . . . . . . . . . . .May 8, 1877 377,374 Telegraphy . . . . . . . . . . . . . . .May 8, 1877 453,601 Sextuplex Telegraph. . . . . . . . . . May 31, 1877 452,913 Sextuplex Telegraph. . . . . . . . . . May 31, 1877 512,872 Sextuplex Telegraph. . . . . . . . . . May 31, 1877 474,231 Speaking Telegraph . . . . . . . . . . July 9, 1877 203,014 Speaking Telegraph . . . . . . . . . .July 16, 1877 208,299 Speaking Telegraph . . . . . . . . . .July 16, 1877 203,015 Speaking Telegraph . . . . . . . . . .Aug. 16, 1877 420,594 Quadruplex Telegraph . . . . . . . . .Aug. 16, 1877 492,789 Speaking Telegraph . . . . . . . . . .Aug. 31, 1877 203,013 Speaking Telegraph . . . . . . . . . . Dec. 8, 1877 203 018 Telephone or Speaking Telegraph. . . . Dec. 8, 1877 200 521 Phonograph or Speaking Machine . . . .Dec. 15, 1877

1878

203,019 Circuit for Acoustic or Telephonic Telegraphs . . . . . . . . . . . . . .Feb. 13, 1878 201,760 Speaking Machines. . . . . . . . . . .Feb. 28, 1878 203,016 Speaking Machines. . . . . . . . . . .Feb. 28, 1878 203,017 Telephone Call Signals . . . . . . . .Feb. 28, 1878 214,636 Electric Lights. . . . . . . . . . . . Oct. 5, 1878 222,390 Carbon Telephones. . . . . . . . . . . Nov. 8, 1878 217,782 Duplex Telegraphs. . . . . . . . . . .Nov. 11, 1878 214,637 Thermal Regulator for Electric Lights.Nov. 14, 1878 210,767 Vocal Engines. . . . . . . . . . . . .Aug. 31, 1878 218,166 Magneto Electric Machines. . . . . . . Dec. 3, 1878 218,866 Electric Lighting Apparatus. . . . . . Dec. 3, 1878 219,628 Electric Lights. . . . . . . . . . . . Dec. 3, 1878 295,990 Typewriter . . . . . . . . . . . . . . Dec. 4, 1878 218,167 Electric Lights. . . . . . . . . . . .Dec. 31, 1878

1879

224,329 Electric Lighting Apparatus. . . . . .Jan. 23, 1879 227,229 Electric Lights. . . . . . . . . . . .Jan. 28, 1879 227,227 Electric Lights. . . . . . . . . . . . Feb. 6, 1879 224.665 Autographic Stencils for Printing. . March 10, 1879 227.679 Phonograph . . . . . . . . . . . . . March 19, 1879 221,957 Telephone. . . . . . . . . . . . . . March 24, 1879 227,229 Electric Lights. . . . . . . . . . . April 12, 1879 264,643 Magneto Electric Machines. . . . . . April 21, 1879 219,393 Dynamo Electric Machines . . . . . . . July 7, 1879 231,704 Electro Chemical Receiving Telephone .July 17, 1879 266,022 Telephone. . . . . . . . . . . . . . . Aug. 1, 1879 252,442 Telephone. . . . . . . . . . . . . . . Aug. 4, 1879 222,881 Magneto Electric Machines. . . . . . .Sept. 4, 1879 223,898 Electric Lamp. . . . . . . . . . . . . Nov. 1, 1879

1880

230,255 Electric Lamps . . . . . . . . . . . .Jan. 28, 1880 248,425 Apparatus for Producing High Vacuums Jan.28 1880 265,311 Electric Lamp and Holder for Same. . . Jan. 28 1880 369,280 System of Electrical Distribution. . .Jan. 28, 1880 227,226 Safety Conductor for Electric Lights .March 10,1880 228,617 Brake for Electro Magnetic Motors. . March 10, 1880 251,545 Electric Meter . . . . . . . . . . . March 10, 1880 525,888 Manufacture of Carbons for Electric Lamps. . . . . . . . . . . . . . . . March 10, 1880 264,649 Dynamo or Magneto Electric Machines. March 11, 1880
228,329 Magnetic Ore Separator . . . . . . . .April 3, 1880 238,868 Manufacture of Carbons for Incandescent Electric Lamps . . . . . . . . . . . April 25, 1880 237,732 Electric Light . . . . . . . . . . . .June 15, 1880 248,417 Manufacturing Carbons for Electric Lights . . . . . . . . . . . . . . . .June 15, 1880 298,679 Treating Carbons for Electric Lights .June 15, 1880 248,430 Electro Magnetic Brake . . . . . . . . July 2, 1880 265,778 Electro Magnetic Railway Engine. . . . July 3, 1880 248,432 Magnetic Separator . . . . . . . . . .July 26, 1880 239,150 Electric Lamp. . . . . . . . . . . . .July 27, 1880 239,372 Testing Electric Light Carbons–Edison and Batchelor. . . . . . . . . . . . .July 28, 1880 251,540 Carbon Electric Lamps. . . . . . . . .July 28, 1880 263,139 Manufacture of Carbons for Electric Lamps. . . . . . . . . . . . . . . . .July 28, 1880 434,585 Telegraph Relay. . . . . . . . . . . .July 29, 1880 248 423 Carbonizer . . . . . . . . . . . . . .July 30, 1880 263 140 Dynamo Electric Machines . . . . . . .July 30, 1880 248,434 Governor for Electric Engines. . . . .July 31, 1880 239,147 System of Electric Lighting. . . . . .July 31, 1880 264,642 Electric Distribution and Translation System . . . . . . . . . . . . . . . . Aug. 4, 1880 293,433 Insulation of Railroad Tracks used for Electric Circuits. . . . . . . . . . . Aug. 6, 1880 239,373 Electric Lamp. . . . . . . . . . . . . Aug. 7, 1880 239,745 Electric Lamp. . . . . . . . . . . . . Aug. 7, 1880 263,135 Electric Lamp. . . . . . . . . . . . . Aug. 7, 1880 251,546 Electric Lamp. . . . . . . . . . . . .Aug. 10, 1880 239,153 Electric Lamp. . . . . . . . . . . . .Aug. 11, 1880 351,855 Electric Lamp. . . . . . . . . . . . .Aug. 11, 1880 248,435 Utilizing Electricity as Motive Power.Aug. 12, 1880 263,132 Electro Magnetic Roller. . . . . . . .Aug. 14, 1880 264,645 System of Conductors for the Distribution of Electricity . . . . . . . . . . . .Sept. 1, 1880 240,678 Webermeter . . . . . . . . . . . . . Sept. 22, 1880 239,152 System of Electric Lighting. . . . . .Oct. 14, 1880 239,148 Treating Carbons for Electric Lights .Oct. 15, 1880 238,098 Magneto Signalling Apparatus–Edison and Johnson. . . . . . . . . . . . . .Oct. 21, 1880 242,900 Manufacturing Carbons for Electric Lamps. . . . . . . . . . . . . . . . .Oct. 21, 1880 251,556 Regulator for Magneto or Dynamo Electric Machines. . . . . . . . . . .Oct. 21, 1880 248,426 Apparatus for Treating Carbons for Electric Lamps . . . . . . . . . . . . Nov. 5, 1880 239,151 Forming Enlarged Ends on Carbon Filaments. . . . . . . . . . . . . . .Nov. 19, 1880 12,631 Design Patent–Incandescent Electric Lamp . . . . . . . . . . . . . . . . .Nov. 23, 1880 239,149 Incandescing Electric Lamp . . . . . . Dec. 3, 1880 242,896 Incandescent Electric Lamp . . . . . . Dec. 3, 1880 242,897 Incandescent Electric Lamp . . . . . . Dec. 3, 1880 248,565 Webermeter . . . . . . . . . . . . . . Dec. 3, 1880 263,878 Electric Lamp. . . . . . . . . . . . . Dec. 3, 1880 239,154 Relay for Telegraphs . . . . . . . . .Dec. 11, 1880 242,898 Dynamo Electric Machine. . . . . . . .Dec. 11, 1880 248,431 Preserving Fruit . . . . . . . . . . .Dec. 11, 1880 265,777 Treating Carbons for Electric Lamps. .Dec. 11, 1880 239,374 Regulating the Generation of Electric Currents . . . . . . . . . . . . . . .Dec. 16, 1880 248,428 Manufacture of Incandescent Electric Lamps. . . . . . . . . . . . . . . . .Dec. 16, 1880 248,427 Apparatus for Treating Carbons for Electric Lamps . . . . . . . . . . . .Dec. 21, 1880 248,437 Apparatus for Treating Carbons for Electric Lamps . . . . . . . . . . . .Dec. 21, 1880 248,416 Manufacture of Carbons for Electric Lights . . . . . . . . . . . . . . . .Dec. 30, 1880

1881

242,899 Electric Lighting. . . . . . . . . . .Jan. 19, 1881 248,418 Electric Lamp. . . . . . . . . . . . . Jan. 19 1881 248,433 Vacuum Apparatus . . . . . . . . . . . Jan. 19 1881 251,548 Incandescent Electric Lamps. . . . . .Jan. 19, 1881 406,824 Electric Meter . . . . . . . . . . . .Jan. 19, 1881 248,422 System of Electric Lighting. . . . . .Jan. 20, 1881 431,018 Dynamo or Magneto Electric Machine . . Feb. 3, 1881 242,901 Electric Motor . . . . . . . . . . . .Feb. 24, 1881 248,429 Electric Motor . . . . . . . . . . . .Feb. 24, 1881 248,421 Current Regulator for Dynamo Electric Machine. . . . . . . . . . . . . . . .Feb. 25, 1881 251,550 Magneto or Dynamo Electric Machines. .Feb. 26, 1881 251,555 Regulator for Dynamo Electric
Machines . . . . . . . . . . . . . . .Feb. 26, 1881 482,549 Means for Controlling Electric Generation . . . . . . . . . . . . . .March 2, 1881 248,420 Fixture and Attachment for Electric Lamps. . . . . . . . . . . . . . . . .March 7, 1881 251,553 Electric Chandeliers . . . . . . . . .March 7, 1881 251,554 Electric Lamp and Socket or Holder . .March 7, 1881 248,424 Fitting and Fixtures for Electric Lamps. . . . . . . . . . . . . . . . .March 8, 1881 248,419 Electric Lamp. . . . . . . . . . . . March 30, 1881 251,542 System of Electric Light . . . . . . April 19, 1881 263,145 Making Incandescents . . . . . . . . April 19, 1881 266,447 Electric Incandescent Lamp . . . . . April 21, 1881 251,552 Underground Conductors . . . . . . . April 22, 1881 476,531 Electric Lighting System . . . . . . April 22, 1881 248,436 Depositing Cell for Plating the Connections of Electric Lamps. . . . . . . . . . . May 17, 1881 251,539 Electric Lamp. . . . . . . . . . . . . May 17, 1881 263,136 Regulator for Dynamo or Magneto Electric Machine . . . . . . . . . . . May 17, 1881 251,557 Webermeter . . . . . . . . . . . . . . May 19, 1881 263,134 Regulator for Magneto Electric Machine. . . . . . . . . . . . . . . . May 19, 1881 251,541 Electro Magnetic Motor . . . . . . . . May 20, 1881 251,544 Manufacture of Electric Lamps. . . . . May 20, 1881 251,549 Electric Lamp and the Manufacture thereof. . . . . . . . . . . . . . . . May 20, 1881 251,558 Webermeter . . . . . . . . . . . . . . May 20, 1881 341,644 Incandescent Electric Lamp . . . . . . May 20, 1881 251,551 System of Electric Lighting. . . . . . May 21, 1881 263,137 Electric Chandelier. . . . . . . . . . May 21, 1881 263,141 Straightening Carbons for Incandescent Lamps. . . . . . . . . . . . . . . . . May 21, 1881 264,657 Incandescent Electric Lamps. . . . . . May 21, 1881 251,543 Electric Lamp. . . . . . . . . . . . . May 24, 1881 251,538 Electric Light . . . . . . . . . . . . May 27, 1881 425,760 Measurement of Electricity in Distribution System . . . . . . . . . . . . . . . .May 3 1, 1881 251,547 Electrical Governor. . . . . . . . . . June 2, 1881 263,150 Magneto or Dynamo Electric Machines. June 3, 1881 263,131 Magnetic Ore Separator . . . . . . . . June 4, 1881 435,687 Means for Charging and Using Secondary Batteries. . . . . . . . . . . . . . .June 21, 1881 263,143 Magneto or Dynamo Electric Machines. .June 24, 1881 251,537 Dynamo Electric Machine. . . . . . . .June 25, 1881 263,147 Vacuum Apparatus . . . . . . . . . . .July 1, 188 1 439,389 Electric Lighting System . . . . . . . July 1, 1881 263,149 Commutator for Dynamo or Magneto Electric Machines. . . . . . . . . . .July 22, 1881 479,184 Facsimile Telegraph–Edison and Kenny.July 26, 1881 400,317 Ore Separator. . . . . . . . . . . . .Aug. 11, 1881 425,763 Commutator for Dynamo Electric Machines . . . . . . . . . . . . . . .Aug. 20, 1881 263,133 Dynamo or Magneto Electric Machine . .Aug. 24, 1881 263,142 Electrical Distribution System . . . .Aug. 24, 1881 264,647 Dynamo or Magneto Electric Machines. .Aug. 24, 1881 404,902 Electrical Distribution System . . . .Aug. 24, 1881 257,677 Telephone. . . . . . . . . . . . . . .Sept. 7, 1881 266,021 Telephone. . . . . . . . . . . . . . .Sept. 7, 1881 263,144 Mold for Carbonizing Incandescents . Sept. 19, 1881 265,774 Maintaining Temperatures in
Webermeters. . . . . . . . . . . . . Sept. 21, 1881 264,648 Dynamo or Magneto Electric Machines. Sept. 23, 1881 265,776 Electric Lighting System . . . . . . Sept. 27, 1881 524,136 Regulator for Dynamo Electrical Machines . . . . . . . . . . . . . . Sept. 27, 1881 273,715 Malleableizing Iron. . . . . . . . . . Oct. 4, 1881 281,352 Webermeter . . . . . . . . . . . . . . Oct. 5, 1881 446,667 Locomotives for Electric Railways. . .Oct. 11, 1881 288,318 Regulator for Dynamo or Magneto Electric Machines. . . . . . . . . . .Oct. 17, 1881 263,148 Dynamo or Magneto Electric Machines. Oct. 25, 1881 264,646 Dynamo or Magneto Electric Machines. Oct. 25, 1881 251,559 Electrical Drop Light. . . . . . . . .Oct. 25, 1881 266,793 Electric Distribution System . . . . .Oct. 25, 1881 358,599 Incandescent Electric Lamp . . . . . .Oct. 29, 1881 264,673 Regulator for Dynamo Electric Machine. Nov. 3, 1881 263,138 Electric Arc Light . . . . . . . . . . Nov. 7, 1881 265,775 Electric Arc Light . . . . . . . . . . .Nov. 7 1881 297,580 Electric Arc Light . . . . . . . . . . .Nov. 7 1881 263,146 Dynamo Magneto Electric Machines . . .Nov. 22, 1881 266,588 Vacuum Apparatus . . . . . . . . . . .Nov. 25, 1881 251,536 Vacuum Pump. . . . . . . . . . . . . . Dec. 5, 1881 264,650 Manufacturing Incandescent Electric Lamps. . . . . . . . . . . . . . . . . Dec. 5, 1881 264,660 Regulator for Dynamo Electric
Machines . . . . . . . . . . . . . . . Dec. 5, 1881 379,770 Incandescent Electric Lamp . . . . . . Dec. 5, 1881 293,434 Incandescent Electric Lamp . . . . . . Dec. 5, 1881 439,391 Junction Box for Electric Wires. . . . Dec. 5, 1881 454,558 Incandescent Electric Lamp . . . . . . Dec. 5, 1881 264,653 Incandescent Electric Lamp . . . . . .Dec. 13, 1881 358,600 Incandescing Electric Lamp . . . . . .Dec. 13, 1881 264,652 Incandescent Electric Lamp . . . . . .Dec. 15, 1881 278,419 Dynamo Electric Machines . . . . . . .Dec. 15, 1881

1882

265,779 Regulator for Dynamo Electric Machines . . . . . . . . . . . . . . .Jan. 17, 1882 264,654 Incandescent Electric Lamps. . . . . .Feb. 10, 1882 264,661 Regulator for Dynamo Electric Machines Feb. 10, 1882 264,664 Regulator for Dynamo Electric Machines Feb. 10, 1882 264,668 Regulator for Dynamo Electric Machines Feb. 10, 1882 264,669 Regulator for Dynamo Electric
Machines . . . . . . . . . . . . . . .Feb. 10, 1882 264,671 Regulator for Dynamo Electric
Machines . . . . . . . . . . . . . . .Feb. 10, 1882 275,613 Incandescing Electric Lamp . . . . . .Feb. 10, 1882 401,646 Incandescing Electric Lamp . . . . . .Feb. 10, 1882 264,658 Regulator for Dynamo Electric
Machines . . . . . . . . . . . . . . .Feb. 28, 1882 264,659 Regulator for Dynamo Electric
Machines . . . . . . . . . . . . . . .Feb. 28, 1882 265,780 Regulator for Dynamo Electric
Machines . . . . . . . . . . . . . . .Feb. 28, 1882 265,781 Regulator for Dynamo Electric
Machines . . . . . . . . . . . . . . .Feb. 28, 1882 278,416 Manufacture of Incandescent Electric Lamps. . . . . . . . . . . . . . . . .Feb. 28, 1882 379,771 Regulator for Dynamo Electric
Machines . . . . . . . . . . . . . . .Feb. 28, 1882 272,034 Telephone. . . . . . . . . . . . . . March 30, 1882 274,576 Transmitting Telephone . . . . . . . March 30, 1882 274,577 Telephone. . . . . . . . . . . . . . March 30, 1882 264,662 Regulator for Dynamo Electric
Machines . . . . . . . . . . . . . . . .May 1, 1882 264,663 Regulator for Dynamo Electric
Machines . . . . . . . . . . . . . . . .May 1, 1882 264,665 Regulator for Dynamo Electric
Machines . . . . . . . . . . . . . . . .May 1, 1882 264,666 Regulator for Dynamo Electric
Machines . . . . . . . . . . . . . . . .May 1, 1882 268,205 Dynamo or Magneto Electric
Machine. . . . . . . . . . . . . . . . .May 1, 1882 273,488 Regulator for Dynamo Electric
Machines . . . . . . . . . . . . . . . .May 1, 1882 273,492 Secondary Battery. . . . . . . . . . . May 19, 1882 460,122 Process of and Apparatus for
Generating Electricity . . . . . . . . May 19, 1882 466,460 Electrolytic Decomposition . . . . . .May 19,. 1882 264,672 Regulator for Dynamo Electric
Machines . . . . . . . . . . . . . . . May 22, 1882 264,667 Regulator for Dynamo Electric
Machines . . . . . . . . . . . . . . . May 22, 1882 265,786 Apparatus for Electrical Transmission of Power . . . . . . . . . . . . . . . May 22, 1882 273,828 System of Underground Conductors of Electric Distribution. . . . . . . . . May 22, 1882 379,772 System of Electrical Distribution. . . May 22, 1882 274,292 Secondary Battery. . . . . . . . . . . June 3, 1882 281,353 Dynamo or Magneto Electric Machine . . June 3, 1882 287,523 Dynamo or Magneto Electric Machine . . June 3, 1882 365,509 Filament for Incandescent Electric Lamps. . . . . . . . . . . . . . . . . .June 3 1882 446,668 Electric Are Light . . . . . . . . . . .June 3 1882 543,985 Incandescent Conductor for Electric Lamps. . . . . . . . . . . . . . . . . June 3, 1882 264,651 Incandescent Electric Lamps. . . . . . June 9, 1882 264,655 Incandescing Electric Lamps. . . . . . June 9, 1882 264,670 Regulator for Dynamo Electric
Machines . . . . . . . . . . . . . . . June 9, 1882 273,489 Turn-Table for Electric Railway. . . . June 9, 1882 273,490 Electro Magnetic Railway System. . . . June 9, 1882 401,486 System of Electric Lighting. . . . . .June 12, 1882 476,527 System of Electric Lighting. . . . . .June 12, 1882 439,390 Electric Lighting System . . . . . . .June 19, 1882 446,666 System of Electric Lighting. . . . . .June 19, 1882 464,822 System of Distributing Electricity . .June 19, 1882 304,082 Electrical Meter . . . . . . . . . . .June 24, 1882 274,296 Manufacture of Incandescents . . . . . July 5, 1882 264,656 Incandescent Electric Lamp . . . . . . July 7, 1882 265,782 Regulator for Dynamo Electric Machines July 7, 1882 265,783 Regulator for Dynamo Electric Machines July 7, 1882 265,784 Regulator for Dynamo Electric Machines July 7, 1882 265,785 Dynamo Electric Machine. . . . . . . . July 7, 1882 273,494 Electrical Railroad. . . . . . . . . . July 7, 1882 278,418 Translating Electric Currents from High to Low Tension . . . . . . . . . . . . July 7, 1882 293,435 Electrical Meter . . . . . . . . . . . July 7, 1882 334,853 Mold for Carbonizing . . . . . . . . . July 7, 1882 339,278 Electric Railway . . . . . . . . . . . July 7, 1882 273,714 Magnetic Electric Signalling
Apparatus. . . . . . . . . . . . . . . Aug. 5, 1882 282,287 Magnetic Electric Signalling
Apparatus. . . . . . . . . . . . . . . Aug. 5, 1882 448,778 Electric Railway . . . . . . . . . . . Aug. 5, 1882 439,392 Electric Lighting System . . . . . . .Aug. 12, 1882 271,613 Manufacture of Incandescent Electric Lamps. . . . . . . . . . . . . . . . .Aug. 25, 1882 287,518 Manufacture of Incandescent Electric Lamps. . . . . . . . . . . . . . . . .Aug. 25, 1882 406,825 Electric Meter . . . . . . . . . . . .Aug. 25, 1882 439,393 Carbonizing Chamber. . . . . . . . . .Aug. 25, 1882 273,487 Regulator for Dynamo Electric MachinesSept. 12, 1882 297,581 Incandescent Electric Lamp . . . . . Sept. 12, 1882 395,962 Manufacturing Electric Lamps . . . . Sept. 16, 1882 287,525 Regulator for Systems of Electrical Distribution–Edison and C. L.
Clarke . . . . . . . . . . . . . . . . Oct. 4, 1882 365,465 Valve Gear . . . . . . . . . . . . . . Oct. 5, 1882 317,631 Incandescent Electric Lamp . . . . . . Oct. 7, 1882 307,029 Filament for Incandescent Lamp . . . . Oct. 9, 1882 268,206 Incandescing Electric Lamp . . . . . .Oct. 10, 1882 273,486 Incandescing Electric Lamp . . . . . .Oct. 12, 1882 274,293 Electric Lamp. . . . . . . . . . . . .Oct. 14, 1882 275,612 Manufacture of Incandescent Electric Lamps. . . . . . . . . . . . . . . . .Oct. 14, 1882 430,932 Manufacture of Incandescent Electric Lamps. . . . . . . . . . . . . . . . .Oct. 14, 1882 271,616 Regulator for Dynamo Electric
Machines . . . . . . . . . . . . . . .Oct. 16, 1882 543,986 Process for Treating Products Derived from Vegetable Fibres. . . . . . . . .Oct. 17, 1882 543,987 Filament for Incandescent Lamps. . . .Oct. 17, 1882 271,614 Shafting . . . . . . . . . . . . . . .Oct. 19, 1882 271,615 Governor for Dynamo Electric
Machines . . . . . . . . . . . . . . .Oct. 19, 1882 273,491 Regulator for Driving Engines of Electrical Generators. . . . . . . . .Oct. 19, 1882 273,493 Valve Gear for Electrical Generator Engines. . . . . . . . . . . . . . . .Oct. 19, 1882 411,016 Manufacturing Carbon Filaments . . . .Oct. 19, 1882 492,150 Coating Conductors for Incandescent Lamps. . . . . . . . . . . . . . . . .Oct. 19, 1882 273,485 Incandescent Electric Lamps. . . . . .Oct. 26, 1882 317,632 Incandescent Electric Lamps. . . . . .Oct. 26, 1882 317,633 Incandescent Electric Lamps. . . . . .Oct. 26, 1882 287,520 Incandescing Conductor for Electric Lamps. . . . . . . . . . . . . . . . . Nov. 3, 1882 353,783 Incandescent Electric Lamp . . . . . . Nov. 3, 1882 430,933 Filament for Incandescent Lamps. . . . Nov. 3, 1882 274,294 Incandescent Electric Lamp . . . . . .Nov. 13, 1882 281,350 Regulator for Dynamo Electric
Machines . . . . . . . . . . . . . . .Nov. 13, 1882 274,295 Incandescent Electric Lamp . . . . . .Nov. 14, 1882 276,233 Electrical Generator and Motor . . . .Nov. 14, 1882 274,290 System of Electrical Distribution. . .Nov. 20, 1882 274,291 Mold for Carbonizer. . . . . . . . . .Nov. 28, 1882 278,413 Regulator for Dynamo Electric MachinesNov. 28, 1882 278,414 Regulator for Dynamo Electric
Machines . . . . . . . . . . . . . . .Nov. 28, 1882 287,519 Manufacturing Incandescing Electric Lamps. . . . . . . . . . . . . . . . .Nov. 28, 1882 287,524 Regulator for Dynamo Electric
Machines . . . . . . . . . . . . . . .Nov. 28, 1882 438,298 Manufacture of Incandescent Electric Lamps. . . . . . . . . . . . . . . . .Nov. 28, 1882 276,232 Operating and Regulating Electrical Generators . . . . . . . . . . . . . .Dec. 20, 1882

1883

278,415 Manufacture of Incandescent Electric Lamps. . . . . . . . . . . . . . . . .Jan. 13, 1883 278,417 Manufacture of Incandescent Electric Lamps. . . . . . . . . . . . . . . . .Jan. 13, 1883 281,349 Regulator for Dynamo Electric
Machines . . . . . . . . . . . . . . .Jan. 13, 1883 283,985 System of Electrical Distribution. . . Jan. 13 1883 283,986 System o’ Electrical Distribution. . . Jan. 13 1883 459,835 Manufacture of Incandescent Electric Lamps. . . . . . . . . . . . . . . . .Jan. 13, 1883 13,940 Design Patent–Incandescing Electric Lamp . . . . . . . . . . . . . . . . . Feb. 13 1883 280,727 System of Electrical Distribution. . . Feb. 13 1883 395,123 Circuit Controller for Dynamo Machine.Feb. 13, 1883 287,521 Dynamo or Magneto Electric Machine . .Feb. 17, 1883 287,522 Molds for Carbonizing. . . . . . . . .Feb. 17, 1883 438,299 Manufacture of Carbon Filaments. . . .Feb. 17, 1883 446,669 Manufacture of Filaments for Incandescent Electric Lamps . . . . . . . . . . . .Feb. 17, 1883 476,528 Incandescent Electric Lamp . . . . . .Feb. 17, 1883 281,351 Electrical Generator . . . . . . . . .March 5, 1883 283,984 System of Electrical Distribution. . .March 5, 1883 287,517 System of Electrical Distribution. . .March 14,1883 283,983 System of Electrical Distribution. . .April 5, 1883 354,310 Manufacture of Carbon Conductors . . .April 6, 1883 370,123 Electric Meter . . . . . . . . . . . .April 6, 1883 411,017 Carbonizing Flask. . . . . . . . . . .April 6, 1883 370,124 Manufacture of Filament for Incandescing Electric Lamp. . . . . . . . . . . . April 12, 1883 287,516 System of Electrical Distribution. . . .May 8, 1883 341,839 Incandescent Electric Lamp . . . . . . .May 8, 1883 398,774 Incandescent Electric Lamp . . . . . . .May 8, 1883 370,125 Electrical Transmission of Power . . . June 1, 1883 370,126 Electrical Transmission of Power . . . June 1, 1883 370,127 Electrical Transmission of Power . . . June 1, 1883 370,128 Electrical Transmission of Power . . . June 1, 1883 370,129 Electrical Transmission of Power . . . June 1, 1883 370,130 Electrical Transmission of Power . . . June 1, 1883 370,131 Electrical Transmission of Power . . . June 1, 1883 438,300 Gauge for Testing Fibres for
Incandescent Lamp Carbons. . . . . . . June 1, 1883 287,511 Electric Regulator . . . . . . . . . .June 25, 1883 287,512 Dynamo Electric Machine. . . . . . . .June 25, 1883 287,513 Dynamo Electric Machine. . . . . . . .June 25, 1883 287,514 Dynamo Electric Machine. . . . . . . .June 25, 1883 287,515 System of Electrical Distribution. . .June 25, 1883 297,582 Dynamo Electric Machine. . . . . . . .June 25, 1883 328,572 Commutator for Dynamo Electric MachinesJune 25, 1883 430,934 Electric Lighting System . . . . . . .June 25, 1883 438,301 System of Electric Lighting. . . . . .June 25, 1883 297,583 Dynamo Electric Machines . . . . . . .July 27, 1883 304,083 Dynamo Electric Machines . . . . . . .July 27; 1883 304,084 Device for Protecting Electric Light Systems from Lightning . . . . . . . .July 27, 1883 438,302 Commutator for Dynamo Electric Machine. . . . . . . . . . . . . . . .July 27, 1883 476,529 System of Electrical Distribution. . .July 27, 1883 297,584 Dynamo Electric Machine. . . . . . . . Aug. 8, 1883 307,030 Electrical Meter . . . . . . . . . . . Aug. 8, 1883 297,585 Incandescing Conductor for Electric Lamps. . . . . . . . . . . . . . . . Sept. 14, 1883 297,586 Electrical Conductor . . . . . . . . Sept. 14, 1883 435,688 Process and Apparatus for Generating Electricity. . . . . . . . . . . . . Sept. 14, 1883 470,922 Manufacture of Filaments for
Incandescent Lamps . . . . . . . . . Sept. 14, 1883 490,953 Generating Electricity . . . . . . . . Oct. 9, 1883 293,432 Electrical Generator or Motor. . . . .Oct. 17, 1883 307,031 Electrical Indicator . . . . . . . . . Nov. 2, 1883 337,254 Telephone–Edison and Bergmann . . . .Nov. 10, 1883 297,587 Dynamo Electric Machine. . . . . . . .Nov. 16, 1883 298,954 Dynamo Electric Machine. . . . . . . .Nov. 15, 1883 298,955 Dynamo Electric Machine. . . . . . . .Nov. 15, 1883 304,085 System of Electrical Distribution. . .Nov. 15, 1883 509,517 System of Electrical Distribution. . .Nov. 15, 1883 425,761 Incandescent Lamp. . . . . . . . . . .Nov. 20, 1883 304,086 Incandescent Electric Lamp . . . . . .Dec. 15, 1883

1884

298,956 Operating Dynamo Electric Machine. . . Jan. 5, 1884 304,087 Electrical Conductor . . . . . . . . .Jan. 12, 1884 395,963 Incandescent Lamp Filament . . . . . .Jan. 22, 1884 526,147 Plating One Material with Another. . .Jan. 22, 1884 339,279 System of Electrical Distribution. . . Feb. 8, 1884 314,115 Chemical Stock Quotation Telegraph– Edison and Kenny . . . . . . . . . . . Feb. 9, 1884 436,968 Method and Apparatus for Drawing Wire . . . . . . . . . . . . . . . . . June 2, 1884 436,969 Apparatus for Drawing Wire . . . . . . June 2, 1884 438,303 Arc Lamp . . . . . . . . . . . . . . . June 2, 1884 343,017 System of Electrical Distribution. . .June 27, 1884 391,595 System of Electric Lighting. . . . . .July 16, 1884 328,573 System of Electric Lighting. . . . . Sept. 12, 1884 328,574 System of Electric Lighting. . . . . Sept. 12, 1884 328,575 System of Electric Lighting. . . . . Sept. 12, 1884 391,596 Incandescent Electric Lamp . . . . . Sept. 24, 1884 438,304 Electric Signalling Apparatus. . . . Sept. 24, 1884 422,577 Apparatus for Speaking Telephones– Edison and Gilliland . . . . . . . . .Oct. 21, 1884 329,030 Telephone. . . . . . . . . . . . . . . Dec. 3, 1884 422,578 Telephone Repeater . . . . . . . . . . Dec. 9, 1884 422,579 Telephone Repeater . . . . . . . . . . Dec. 9, 1884 340,707 Telephonic Repeater. . . . . . . . . . Dec. 9, 1884 340,708 Electrical Signalling Apparatus. . . .Dec. 19, 1884 347,097 Electrical Signalling Apparatus. . . .Dec. 19, 1884 478,743 Telephone Repeater . . . . . . . . . .Dec. 31, 1884

1885

340,709 Telephone Circuit–Edison and Gilliland. . . . . . . . . . . . . . . Jan. 2, 1885 378,044 Telephone Transmitter. . . . . . . . . Jan. 9, 1885 348,114 Electrode for Telephone Transmitters .Jan. 12, 1885 438,305 Fuse Block . . . . . . . . . . . . . .Jan. 14, 1885 350,234 System of Railway Signalling–Edison and Gilliland. . . . . . . . . . . . .March 27,1885 486,634 System of Railway Signalling–Edison and Gilliland. . . . . . . . . . . . .March 27,1885 333,289 Telegraphy . . . . . . . . . . . . . April 27, 1885 333,290 Duplex Telegraphy. . . . . . . . . . April 30, 1885 333,291 Way Station Quadruplex Telegraph . . . .May 6, 1885 465,971 Means for Transmitting Signals ElectricallyMay 14, 1885 422 072 Telegraphy . . . . . . . . . . . . . . Oct. 7, 1885 437 422 Telegraphy . . . . . . . . . . . . . . Oct. 7, 1885 422,073 Telegraphy . . . . . . . . . . . . . Nov. I 2, 1885 422,074 Telegraphy . . . . . . . . . . . . . .Nov. 24, 1885 435,689 Telegraphy . . . . . . . . . . . . . .Nov. 30, 1885 438,306 Telephone – Edison and Gilliland . . .Dec. 22, 1885 350,235 Railway Telegraphy–Edison and Gilliland. . . . . . . . . . . . . . .Dec. 28, 1885

1886

406,567 Telephone. . . . . . . . . . . . . . .Jan. 28, 1886 474,232 Speaking Telegraph . . . . . . . . . .Feb. 17, 1886 370 132 Telegraphy . . . . . . . . . . . . . . May 11, 1886 411,018 Manufacture of Incandescent Lamps. . .July 15, 1886 438,307 Manufacture of Incandescent Electric Lamps. . . . . . . . . . . . . . . . July I 5, 1886 448,779 Telegraph. . . . . . . . . . . . . . .July IS, 1886 411,019 Manufacture of Incandescent Electric Lamps. . . . . . . . . . . . . . . . .July 20, 1886 406,130 Manufacture of Incandescent Electric Lamps. . . . . . . . . . . . . . . . . Aug. 6, 1886 351,856 Incandescent Electric Lamp . . . . . Sept. 30, 1886 454,262 Incandescent Lamp Filaments. . . . . .Oct. 26, 1886 466,400 Cut-Out for Incandescent Lamps–Edison and J. F. Ott. . . . . . . . . . . . .Oct. 26, 1886 484,184 Manufacture of Carbon Filaments. . . .Oct. 26, 1886 490,954 Manufacture of Carbon Filaments for Electric Lamps . . . . . . . . . . . . Nov. 2, 1886 438,308 System of Electrical Distribution. . . Nov. 9, 1886 524,378 System of Electrical Distribution. . . Nov. 9, 1886 365,978 System of Electrical Distribution. . .Nov. 22, 1886 369 439 System of Electrical Distribution. . .Nov. 22, 1886 384 830 Railway Signalling–Edison and GillilandNov. 24, 1886 379,944 Commutator for Dynamo Electric MachinesNov. 26, 1886 411,020 Manufacture of Carbon Filaments. . . .Nov. 26, 1886 485,616 Manufacture of Carbon Filaments. . . . .Dec 6, 1886 485,615 Manufacture of Carbon Filaments. . . . .Dec 6, 1886 525,007 Manufacture of Carbon Filaments. . . . Dec. 6, 1886 369,441 System of Electrical Distribution. . .Dec. 10, 1886 369,442 System of Electrical Distribution. . .Dec. 16, 1886 369,443 System of Electrical Distribution. . .Dec. 16, 1886 484,185 Manufacture of Carbon Filaments. . . .Dec. 20, 1886 534,207 Manufacture of Carbon Filaments. . . .Dec. 20, 1886 373,584 Dynamo Electric Machine. . . . . . . .Dec. 21, 1886

1887

468,949 Converter System for Electric Railways . . . . . . . . . . . . . . . Feb. 7, 1887 380,100 Pyromagnetic Motor . . . . . . . . . . May 24, 1887 476,983 Pyromagnetic Generator . . . . . . . . .May 24 1887 476,530 Incandescent Electric Lamp . . . . . . June 1, 1887 377,518 Magnetic Separator . . . . . . . . . .June 30, 1887 470,923 Railway Signalling . . . . . . . . . . Aug. 9, 1887 545,405 System of Electrical Distribution. . .Aug. 26, 1887 380,101 System of Electrical Distribution. . .Sept. 13 1887 380,102 System of Electrical Distribution. . .Sept. 14 1887 470,924 Electric Conductor . . . . . . . . . Sept. 26, 1887 563,462 Method of and Apparatus for Drawing Wire . . . . . . . . . . . . . . . . .Oct. 17, 1887 385,173 System of Electrical Distribution. . . Nov. 5, 1887 506,215 Making Plate Glass . . . . . . . . . . Nov. 9, 1887 382,414 Burnishing Attachments for PhonographsNov. 22, 1887 386,974 Phonograph . . . . . . . . . . . . . .Nov. 22, 1887 430,570 Phonogram Blank. . . . . . . . . . . .Nov. 22, 1887 382,416 Feed and Return Mechanism for PhonographsNov. 29, 1887 382,415 System of Electrical Distribution. . . Dec. 4, 1887 382,462 Phonogram Blanks . . . . . . . . . . . Dec. 5, 1887

1888

484,582 Duplicating Phonograms . . . . . . . .Jan. 17, 1888 434,586 Electric Generator . . . . . . . . . .Jan. 21, 1888 434,587 Thermo Electric Battery. . . . . . . .Jan. 21, 1888 382,417 Making Phonogram Blanks. . . . . . . .Jan. 30, 1888 389,369 Incandescing Electric Lamp . . . . . . Feb. 2, 1888 382,418 Phonogram Blank. . . . . . . . . . . .Feb. 20, 1888 390,462 Making Carbon Filaments. . . . . . . .Feb. 20, 1888 394,105 Phonograph Recorder. . . . . . . . . .Feb. 20, 1888 394,106 Phonograph Reproducer. . . . . . . . .Feb. 20, 1888 382,419 Duplicating Phonograms . . . . . . . .March 3, 1888 425,762 Cut-Out for Incandescent Lamps . . . .March 3, 1888 396,356 Magnetic Separator . . . . . . . . . .March 19,1888 393,462 Making Phonogram Blanks. . . . . . . April 28, 1888 393,463 Machine for Making Phonogram Blanks. April 28, 1888 393,464 Machine for Making Phonogram Blanks. April 28, 1888 534,208 Induction Converter. . . . . . . . . . .May 7, 1888 476,991 Method of and Apparatus for Separating Ores . . . . . . . . . . . . . . . . . .May 9, 1888 400,646 Phonograph Recorder and Reproducer . . May 22, 1888 488,190 Phonograph Reproducer. . . . . . . . . May 22, 1888 488,189 Phonograph . . . . . . . . . . . . . . May 26, 1888 470,925 Manufacture of Filaments for Incandescent Electric Lamps . . . . . . . . . . . .June 21, 1888 393,465 Preparing Phonograph Recording SurfacesJune 30, 1888 400,647 Phonograph . . . . . . . . . . . . . .June 30, 1888 448,780 Device for Turning Off Phonogram BlanksJune 30, 1888 393,466 Phonograph Recorder. . . . . . . . . .July 14, 1888 393,966 Recording and Reproducing Sounds . . .July 14, 1888 393,967 Recording and Reproducing Sounds . . .July 14, 1888 430,274 Phonogram Blank. . . . . . . . . . . .July 14, 1888 437,423 Phonograph . . . . . . . . . . . . . .July 14, 1888 450,740 Phonograph Recorder. . . . . . . . . .July 14, 1888 485,617 Incandescent Lamp Filament . . . . . .July 14, 1888 448,781 Turning-Off Device for Phonographs . .July 16, 1888 400,648 Phonogram Blank. . . . . . . . . . . .July 27, 1888 499,879 Phonograph . . . . . . . . . . . . . .July 27, 1888 397,705 Winding Field Magnets. . . . . . . . .Aug. 31, 1888 435,690 Making Armatures for Dynamo Electric Machines . . . . . . . . . . . . . . .Aug. 31, 1888 430,275 Magnetic Separator . . . . . . . . . Sept. 12, 1888 474,591 Extracting Gold from Sulphide Ores . Sept. 12, 1888 397,280 Phonograph Recorder and Reproducer . Sept. 19, 1888 397,706 Phonograph . . . . . . . . . . . . . Sept. 29, 1888 400,649 Making Phonogram Blanks. . . . . . . Sept. 29, 1888 400,650 Making Phonogram Blanks. . . . . . . .Oct. 15, 1888 406,568 Phonograph . . . . . . . . . . . . . .Oct. 15, 1888 437,424 Phonograph . . . . . . . . . . . . . .Oct. 15, 1888 393,968 Phonograph Recorder. . . . . . . . . .Oct. 31, 1888

1889

406,569 Phonogram Blank. . . . . . . . . . . .Jan. 10, 1889 488,191 Phonogram Blank. . . . . . . . . . . .Jan. 10, 1889 430,276 Phonograph . . . . . . . . . . . . . .Jan. 12, 1889 406,570 Phonograph . . . . . . . . . . . . . . Feb. 1, 1889 406,571 Treating Phonogram Blanks. . . . . . . Feb. 1, 1889 406,572 Automatic Determining Device for Phonographs. . . . . . . . . . . . . . Feb. 1, 1889 406,573 Automatic Determining Device for Phonographs. . . . . . . . . . . . . . Feb. 1, 1889 406,574 Automatic Determining Device for Phonographs. . . . . . . . . . . . . . Feb. 1, 1889 406,575 Automatic Determining Device for Phonographs. . . . . . . . . . . . . . Feb. 1, 1889 406,576 Phonogram Blank. . . . . . . . . . . . Feb. 1, 1889 430,277 Automatic Determining Device for Phonographs. . . . . . . . . . . . . . Feb. 1, 1889 437,425 Phonograph Recorder. . . . . . . . . . Feb. 1, 1889 414,759 Phonogram Blanks . . . . . . . . . . March 22, 1889 414,760 Phonograph . . . . . . . . . . . . . March 22, 1889 462,540 Incandescent Electric Lamps. . . . . March 22, 1889 430,278 Phonograph . . . . . . . . . . . . . .April 8, 1889 438,309 Insulating Electrical Conductors . . April 25, 1889 423,039 Phonograph Doll or Other Toys. . . . .June 15, 1889 426,527 Automatic Determining Device for Phonographs. . . . . . . . . . . . . .June 15, 1889 430,279 Voltaic Battery. . . . . . . . . . . .June 15, 1889 506,216 Apparatus for Making Glass . . . . . .June 29, 1889 414,761 Phonogram Blanks . . . . . . . . . . .July 16, 1889 430,280 Magnetic Separator . . . . . . . . . .July 20, 1889 437,426 Phonograph . . . . . . . . . . . . . .July 20, 1889 465,972 Phonograph . . . . . . . . . . . . . .Nov. 14, 1889 443,507 Phonograph . . . . . . . . . . . . . . Dec. 11 1889 513,095 Phonograph . . . . . . . . . . . . . . Dec. 11 1889

1890

434,588 Magnetic Ore Separator–Edison and W. K. L. Dickson . . . . . . . . . . .Jan. 16, 1890 437,427 Making Phonogram Blanks. . . . . . . . Feb. 8, 1890 465,250 Extracting Copper Pyrites. . . . . . . Feb. 8, 1890 434,589 Propelling Mechanism for Electric VehiclesFeb. 14, 1890 438,310 Lamp Base. . . . . . . . . . . . . . April 25, 1890 437,428 Propelling Device for Electric Cars. April 29, 1890 437,429 Phonogram Blank. . . . . . . . . . . April 29, 1890 454,941 Phonograph Recorder and Reproducer . . .May 6, 1890 436,127 Electric Motor . . . . . . . . . . . . May 17, 1890 484,583 Phonograph Cutting Tool. . . . . . . . May 24, 1890 484,584 Phonograph Reproducer. . . . . . . . . May 24, 1890 436,970 Apparatus for Transmitting Power . . . June 2, 1890 453,741 Phonograph . . . . . . . . . . . . . . July 5, 1890 454,942 Phonograph . . . . . . . . . . . . . . July 5, 1890 456,301 Phonograph Doll. . . . . . . . . . . . July 5, 1890 484,585 Phonograph . . . . . . . . . . . . . . July 5, 1890 456,302 Phonograph . . . . . . . . . . . . . . Aug. 4, 1890 476,984 Expansible Pulley. . . . . . . . . . . Aug. 9, 1890 493,858 Transmission of Power. . . . . . . . . Aug. 9, 1890 457,343 Magnetic Belting . . . . . . . . . . .Sept. 6, 1890 444,530 Leading-in Wires for Incandescent Electric Lamps (reissued October 10, 1905,
No. 12,393). . . . . . . . . . . . . Sept. 12, 1890 534 209 Incandescent Electric Lamp . . . . . Sept. 13, 1890 476 985 Trolley for Electric Railways. . . . .Oct. 27, 1890 500,280 Phonograph . . . . . . . . . . . . . .Oct. 27, 1890 541,923 Phonograph . . . . . . . . . . . . . .Oct. 27, 1890 457,344 Smoothing Tool for Phonogram
Blanks . . . . . . . . . . . . . . . .Nov. 17, 1890 460,123 Phonogram Blank Carrier. . . . . . . .Nov. 17, 1890 500,281 Phonograph . . . . . . . . . . . . . .Nov. 17, 1890 541,924 Phonograph . . . . . . . . . . . . . .Nov. 17, 1890 500,282 Phonograph . . . . . . . . . . . . . . Dec. 1, 1890 575,151 Phonograph . . . . . . . . . . . . . . Dec. 1, 1890 605,667 Phonograph . . . . . . . . . . . . . . Dec. 1, 1890 610,706 Phonograph . . . . . . . . . . . . . . Dec. 1, 1890 622,843 Phonograph . . . . . . . . . . . . . . Dec. 1, 1890 609,268 Phonograph . . . . . . . . . . . . . . Dec. 6, 1890 493,425 Electric Locomotive. . . . . . . . . .Dec. 20, 1890

1891

476,992 Incandescent Electric Lamp . . . . . .Jan. 20, 1891 470,926 Dynamo Electric Machine or Motor . . . Feb. 4, 1891 496,191 Phonograph . . . . . . . . . . . . . . Feb. 4, 1891 476,986 Means for Propelling Electric Cars . .Feb. 24, 1891 476,987 Electric Locomotive. . . . . . . . . .Feb. 24, 1891 465,973 Armatures for Dynamos or Motors. . . .March 4, 1891 470,927 Driving Mechanism for Cars . . . . . .March 4, 1891 465,970 Armature Connection for Motors or Generators . . . . . . . . . . . . . March 20, 1891 468,950 Commutator Brush for Electric Motors and Dynamos. . . . . . . . . . . . . March 20, 1891 475,491 Electric Locomotive. . . . . . . . . . June 3, 1891 475,492 Electric Locomotive. . . . . . . . . . June 3, 1891 475,493 Electric Locomotive. . . . . . . . . . June 3, 1891 475,494 Electric Railway . . . . . . . . . . . June 3, 1891 463,251 Bricking Fine Ores . . . . . . . . . .July 31, 1891 470,928 Alternating Current Generator. . . . .July 31, 1891 476,988 Lightning Arrester . . . . . . . . . .July 31, 1891 476,989 Conductor for Electric Railways. . . .July 31, 1891 476,990 Electric Meter . . . . . . . . . . . .July 31, 1891 476,993 Electric Arc . . . . . . . . . . . . .July 31, 1891 484,183 Electrical Depositing Meter. . . . . .July 31, 1891 485,840 Bricking Fine Iron Ores. . . . . . . .July 31, 1891 493,426 Apparatus for Exhibiting Photographs of Moving Objects. . . . . . . . . . .July 31, 1891 509,518 Electric Railway . . . . . . . . . . .July 31, 1891 589,168 Kinetographic Camera (reissued September 30, 1902, numbered 12,037
and 12,038, and January 12, 1904, numbered 12,192) . . . . . . . . . . .July 31, 1891 470,929 Magnetic Separator . . . . . . . . . .Aug. 28, 1891 471,268 Ore Conveyor and Method of Arranging Ore Thereon. . . . . . . . . . . . . .Aug. 28, 1891 472,288 Dust-Proof Bearings for Shafts . . . .Aug. 28, 1891 472,752 Dust-Proof Journal Bearings. . . . . .Aug. 28, 1891 472,753 Ore-Screening Apparatus. . . . . . . .Aug. 28, 1891 474,592 Ore-Conveying Apparatus. . . . . . . .Aug. 28, 1891 474,593 Dust-Proof Swivel Shaft Bearing. . . .Aug. 28, 1891 498,385 Rollers for Ore-Crushing or Other Material . . . . . . . . . . . . . . .Aug. 28, 1891 470,930 Dynamo Electric Machine. . . . . . . . .Oct 8, 1891 476,532 Ore-Screening Apparatus. . . . . . . . .Oct 8, 1891 491,992 Cut-Out for Incandescent Electric LampsNov. 10, 1891

1892

491,993 Stop Device. . . . . . . . . . . . . . April 5 1892 564,423 Separating Ores. . . . . . . . . . . .June 2;, 1892 485,842 Magnetic Ore Separation. . . . . . . . July 9, 1892 485,841 Mechanically Separating Ores . . . . . July 9, 1892 513,096 Method of and Apparatus for Mixing Materials. . . . . . . . . . . . . . .Aug. 24, 1892

1893

509,428 Composition Brick and Making Same. . March 15, 1893 513,097 Phonograph . . . . . . . . . . . . . . May 22, 1893 567,187 Crushing Rolls . . . . . . . . . . . .Dec. 13, 1893