PAGE. Railway and illuminating plant of the Mil- Spark arrester, Chicago... Specific electrostatic capacity and specific ether PAGE A 269 .N 537 New trolley roads.. .N 10 66 66 Should electric supply power to indi- viduals?... E 235 66 and electrolysis. Rapid transit, New York's hope of Recenti Progressi Nelle Applicazioni Dell' Recording wattmeter for arc circuits Thomson *T N 243 "Records for the benefit of printers.". Reflectors, Gleason's. Relative advantages of toothed and smooth core .E 374 F. 475 66 recorder for electric cars, Henry.L 165, *A 323 .R 440 rules for electrical construction and 201 66 Tables for Electric Wiremen. Bv Government suit to annul the Ber- Standardizing electrical measuring instruments 66 in Germany. N 74 66 *A 505 Star ventilator, Infringement of.. TN 147 Station construction, Arnold system...... *A 436 Ax 163 66 of the Edison Electric Illuminating Co. *A 178 Stations, paying.. E 188, L 191 .N 444, 499 N 126 Rowland's method of cooling transformers and Royal Electric Co 66 Rules for electrical construction and operation. 201 66 N. E. L. A. standard.. Rushmore drum armature winding........*T *A 157 Statistical Association, National. E 70 N 188 R 369 Steam heating, Exhaust. N 462 Progress of. I. H. Bab- A 295 .N 499 TN 60 *A 408 ..N 259 service at message rates. Steering by, in a fog... N 76 .E 51 N 522 E 474 *T N 194 66 switchboard, National... W. Manson. *TN 380 troubles, locating, The. By H. L. Webb. transmitter, Cook extension....*T N 382 wires. Self-induction and bi-metal- atus.. *TN 222 Tert book of Electro-Magnetism and the Con- Tway circuits... *T N 291 66 66 on the Pyramids..... N 426 Taxation by free passes.. Sign of the Times.. E 135 Signals and trolley currents. N 533 Taxing telegraph poles in Alabama. Silvey storage car system.. *A 298 Single motor equipment for street railways, *A 496 66 66 E 13 trolley system at Portland, Ore..*Ax 478 Toledo, Monroe & Detroit Electric Railway... N 549 N 495 Single-phase circuits, Motors operated by.*A 4, E 12 Traccion electrica sistema de Love. .R 518 A 10 .N 498 Small arc lamps. 64 44 Elihu Thomson. Traité de Télégraphie Electrique. By H. .R 518 resonance, Pupin's Transformers, Air-core, 66 46 66 66 system.... *A 509 in Cleveland Dr. Pupin on the behavior of air- .N 138 *TN 58 .L 261 Telegraph-1844-1894 Joseph Henry's place in the history PAGE. *A 89 .*TN 194 Voltmeters for direct and alternating currents, W Waddell-Entz Co.. Embarrassment of.... N 166 Wagner Electric Mfg. Co..... TN 59 Bergmann, S.. Berry, T. H.. ....... 284 H. A.... ...N 16 .198, 491 A 385 power by A 467, 491 Wagon, electrical advertising.. Canfield, M. C. 277 *T N 423 Carhart, H. S. 72, 90, 112 .TN 313 Crehore, A. C. 261 TN 80 66 Crocker, F. B. 468 Cushing, H. C., Jr.... .229, 306, 410 Debell, E. L... 141 Dennis, J, Jr.................. 245 371 แ Street railway apparatus of...*A 309 Wallace Electric Co... TN 80 Warren alternate current engine-dynamo ..*A 361 Water power plant of the Concord Land & Water Power Co. A. C. Shaw... Wattmeter, Bristol's Recording... 66 *T N 503 for arc circuits, Thomson Recording Donaldson, W. W. Duncan, Louis. Edson, J. B.. .*IN 243 Emery, C. E.. :: for street car testing, Thomson Recording.... Emmet, W. L. R.. .N 138 *A 425 Thomson recording arc....... Weber telephone attachment... *T N 267 N 329 Ewing, J. A........ ...TN 79 Ewing, T., Jr Webster separators, World's Fair test.... TN 168 Foote, A. R...... .A 25 66 & Co., Warren.. TN 334 Forbes, Geo....... .... Weight of electric motors.. ..L 517 Frick, Otto.. Genung, N. H. phase... N 56 *A 402 proposed in California.. 257 .449, 510 42, 467 417 304 .372, 896 .165, 286, 536 .14, 84 225, 247, 274 325 .165, 219, 286 44 at Taftville, Conn., Three Relative economy of copper in single phase.two phase and three phase. W. L. R. Emmet.... *A 42 Transmissione Eletricca del Lavora Meccanico. R 411 By G Sartori... Transparent conducting screens for electric and other apparatus... ..Ax 417 Transportation department. Electric....6, 32, 48, 68. 109, 186, 160, 179, 230, 252, 281, 298, 822, 414, 432, 478, 496, 581, 549 Triphase power transmission at Columbia, S. C. "Triumph" iron-clad dynamo. Trolley clamp, "Chicago." current, How to make it "deadly."...N 429 66 currents and railroad signals.... extension in Brooklyn..... *T N 315 .N 533 .E 515 N 549 ....N 283 ..N 69 66 overhead circuits.. E 494 Co. and the Niagara contract... combined direct and alternating current generator at Rochester, N. Y. John Dennis, Jr...*A 245 direct current arc generator*T N 265 Electric & Mfg. Co... ......T N 421 Machine Co., Ownership of..T N 56 motors for Boston West End..N 283 plans for Niagara contract.....A 25 railway motors and controller*A 393 report..... Weston engines...... telegraph relay. West Virginia University, Electrical wanted.... What are wiring rules made for ?. E 435 TN 482 A 157 apparatus TN 422 L 260 N 329 37 TN 146 Law, M. D Leonard, H. W. Mather, T. McFadden, P. J.. Merrill, E. A.. ... .................. ..... 537 417 179 491 241, 366 62 65 479 153 Vol. XVII. THE Electrical Engineer. JANUARY 3, 1894. W HILE reading Miss Henry's remarkable presentation of her father's great work in connection with the Electric Telegraph-remarkable in the power she has shown in grasping the essential features of her father's labors-I was reminded of my first interview with Joseph Henry. One morning he came into my laboratory at Cambridge, and, after I had shown him various pieces of scientific apparatus, he stood before an electro-magnet which was working a relay and looked long at the magnet, and then at the battery which was coupled for quantity, and remarked in a quiet tone, as if half to himself, "If I had patented that arrangement of magnet and battery I should have reaped great pecuniary reward for my discovery of the practical method of telegraphy." Miss Henry can speak with authority upon her father's aims and labors, and the conclusions she draws from his conversations and from his notes and letters are in consonance with the belief which has been steadily growing, that Joseph Henry invented the essential features of telegraphy. JOHN TROWBRIDGE. THE ELECTRO-MAGNET. IN the civilized world is there anything which in this day contributes more to the comfort of man than the electro-magnet? Strike it out of existence and the electric telegraph would die. Its great network of wires would be as useless as the curious system of nerves which carries the message of the brain to the finger tips is useless when that mysterious principle which constitutes the life of the human being has departed. The telegraph gone, distant countries would unclasp hands, as were, and the wide ocean roll again between. The eager world would be struck dumb in the midst of its innumerable political, commercial and social relations; or, rather, would be sent back to the stammering old time when months intervened in the exchange of thought, now possible in an hour. But not alone as the soul of the telegraph would the loss of the electro-magnet be felt; hardly a moment's thought is needed to realize the place it has gained, the importance its failure to meet the demands. made upon it would be to the world. How did it come into existence-this electro-magnet? Perhaps, considering the importance of the subject, it may bear to be not merely a twice-told, but an oft-repeated tale. Joseph Henry. What is a magnet? Our acquaintance with it began No. 296. in our childhood: as a piece of steel endowed with a mysterious attractive power, it was among our toys; many a time have we held it over a pile of needles and laughed to see them leap to meet it, or with it we have drawn our little boats from the farther side of a mimic sea. How did it receive its name? It is pleasant in imagination to travel far away through the beautiful islands of the Egean sea to the shores of Asia, and to believe in the romantic story which tells us that a Greek shepherd, Magnus by name, wandering over Mt. Ida with his sheep, found his crook suddenly and powerfully attracted by a mass of iron ore, and so attached his humble name to the loadstone or natural magnet. But fancy must yield with reluctance to the more prosaic assumption now generally adopted, that the name was derived from Magnesia, in Lydia, where the ore was first found. For the word electro we must not only come down the mountain, but descend the stream of time to about five hundred years before Christ; then we must follow the undulations of the Ionian coast, to find, at the mouth of the river Meander, the city of Miletus. Walking her streets at this time, caring little for her magnificence or for the wars in which she was engaged, save to induce peace, was Thales, one of the seven wise men of Greece. Among the objects of trade in the magnificent city was the yellow amber; not an object of indifference to the philosopher, although as yet only of frivolous use as an ornament. Its color no doubt delighted his eyes but it had a deeper interest for him. Rubbing the stone one day-perhaps to make its yellow tint clearer-he found that he had endowed it with a curious power: a loose feather flew to meet it. This power seemed to Thales miraculous. He imagined there were spirits in the amber and so came to think that everything in the universe must be pervaded by spirits. Thus electricity was discovered, and it received its name, long afterwards, from the Greek word meaning amber. It was at a very early period that the loadstone or natural magnet was discovered. Very early too was known the remarkable power it possesses of transmitting its properties to hard iron or steel when these bodies are rubbed, or even touched by it. Thus came into being the steel magnet-possessing not only the same power of transmitting its properties but also a quality lacking in the ore; turning north and south, when free to move, in obedience to the great magnet, the earth, it had a directive power which more than two thousand years before the Christian era directed the traveler over the land, as later it was to guide the mariner over the sea. From this remote period it is a long flight down the ages until in England, in the cabinet of the self-taught shoemaker-philosopher, Sturgeon, stood the first electro-magnet; that is, the magnet made by electricity. Of the deepest interest to the scientific world was this little instrument. It consisted of a small bar of soft iron bent into the form of a horse shoe, with a spiral of wire wound loosely around it, the ends of the wire dipping into two cups of mercury. When into these cups the wires from a galvanic battery were also dipped, an electric circuit was formed and the electric current, passing through the spiral of wire, rendered the soft iron bar magnetic. It was very feeble, this magnet; it required a large battery to give it any strength. What advantage could it boast over the steel magnets which had served the world so many years? Some of these were very powerful; one in London at this time belonging to the Royal Society lifted one hundred pounds. These magnets were all permanent steel when endowed with magnetism retains it; not so soft iron. This bent bar of Sturgeon's was a magnet only while the electricity was circulating through the wire around it; in this lay its advantage: it was a magnet, or not, at the will of man. It was not merely as a scientific fact that the world turned to it with such eagerness; it renewed an old hope that electricity might be made the messenger of man. The story of the electro-magnet is but a part of the story of the electric telegraph; we may not tell the one without reference to the other. Sturgeon's Magnet. We cannot go back far enough in the history of man to find a time when the idea of the distant communication of intelligence did not exist. In the earliest childhood of the race even, beacon fires proclaimed from hill to hill tidings of weal or woe. In those early days man looked up with dread to the lightning, thinking it "the eye-flash of an angry god," not dreaming that it was the manifestation of the agent which was to satisfy his long-cherished desire for distant communication with his fellowman, that the very genius of the storm was one day to serve as his messenger. It is interesting to know that Hauksbee of England in 1705 was the first to suspect the identity of lightning and electricity. He produced a thunder-storm in miniature by drawing a piece of amber swiftly through a woolen cloth. He says "a prodigious number of little cracklings were heard, every one of which produced a little flash of light. This light and crackling seem in some degree to represent thunder and lightning." As man learned in various ways, by the rubbing of amber and other substances, to excite electricity, and learned also the value of the force thus produced, also that the electrical influence could be transmitted through several hundred feet of wire, there came to him the conception that by the friction of his machines he might, as Aladdin by the rubbing of his lamp, summon the slave of his will which was to serve in the transmission of intelligence. The first attempts to use electricity for this purpose began in 1753. Who was the first to suggest the idea it seems difficult to determine; it was such a natural idea after the experimental results which had been obtained that it probably occurred to many minds at the same time, and it is only surprising that it was not conceived earlier. We may not here notice any one of the efforts in this line founded thus on frictional or static electricity; they form one of three distinct, although overlapping, eras in the history of the telegraph. They had a measure of success. They were very interesting from a scientific point of view and they served certain ends, but they did not give the telegraph to the world. [By the telegraph I mean here that system or combination by which mechanical effects can be produced at great distances through seas, over continents-and I use the term in contradistinction to the many attempts towards this result, made at various times and in various places which if successful were so only in a limited degree, because the natural laws which control electrical action were undiscovered or unknown. Will the reader be so kind as to take especial notice of this remark; it is necessary for the proper understanding of my story.] In Bologna, in the year 1753, a "religious youth of fourteen years was dreaming of church service, discouraged by his friends; while on the shores of Lake Como was playing a boy of eight;" these two were destined to make the discovery which was to form the second era in the history of the telegraph. In 1789, a dead frog's leg hanging upon a copper hook and kicking as though it were alive whenever the sportive wind blew it against an iron balcony-elec tricity at work, in what seemed almost the enjoyment of a jest-revealed to Galvani that by chemical action, as well as by friction, the genius of the thunder-storm might be evoked. Volta followed with his " couronne de tasses' and thus came into being the Galvanic or Voltaic battery, bearing the names of both men. So general and profound was the interest excited that Napoleon Bonaparte invited Volta to Paris, witnessed his experiments with the instrument in the presence of the National Institute, and loaded him with decorations. More eager now grew the hope of means of distant communication. The electricity of the machine, that is, the electricity produced by friction, had answered for this purpose only in a very limited degree; but this battery,-might not its long wires be extended indefinitely? Might not this current of Volta's, easily excited, easily set at rest, by the mere making or breaking of the contact of those same long wires, at last be the messenger so long desired? Of the many efforts in this direction, led in by Sommering of Munich, we may not speak. Could we follow their fortunes, now in one country, now in another, we would find that, however ingenious, sooner or later they all ended in the same difficulty, viz.: the failure of the electric force with increase in the extent of the conducting wire of the battery. It was but a question of time, or rather of distance; each new effort met the fate of its predecessors. For a while the electric force seemed to lend itself to this service, only to escape and laugh, as it were, at the efforts of the impotent creature, man, to bring it under restraint. We turn now again to the electro-magnet. In a former article we tried to tell, in these pages, how the world found out that electricity could produce magnetism; step by step, from Oersted swaying his needle through the influence of the electric current, down to Ampere magnetizing needles in a glass case by means of electricity; we come back to 1824-25, to the bent iron bar in Sturgeon's cabinet and to the interest it excited. Then indeed the OERSTED'S NEEDLE. telegraph seemed a thing of the near future. There was not only the wonderful Voltaic battery, there was this magnet ready to respond to the will of man; could it not be made thus to respond at a distance? Surely the desire of the world would now be accomplished! Barlow, a distinguished mathematician and engineer of England, essayed the practical experiment with the new instrument, while Europe waited, we might say, with bated breath, in confident expectation for the result. What was it? Again a disappointment. We will let Barlow speak for himself. "The details of the contrivance are SO obvious, the principles so well understood, that there is only this one question which could render the result doubtful. Is there any diminution of effect by lengthening the conducting wire? I was therefore induced to make the trial, but found such a sensible diminution with only two hundred feet of wire as at once to convince me of the impracticability of the scheme." It could not be possible! The experiment was repeated in various ways, in the same year, 1825, and in the following year, but with like result; each experiment confirmed the reluctant conclusion that after all the brilliant discoveries which had excited such eager expectation, an electro-magnetic telegraph was an impossibility. Since Sturgeon's magnet, as well as Volta's battery, had failed, there appeared to be no means of obtaining sufficient electrical force to act at a distance. Had the hope of the telegraph indeed ended, and in disappointment? For want of sufficient electric force the telegraph is an impossibility; such seemed the verdict of the science of Europe, and with it we turn to America. Very brilliant was the old world of science, at that day represented in the line of physics by such men as Hansteen, studying the magnetism of the earth, Gay Lussac and Biot invading even the blue air in the search after the magnetic forces, the immortal Arago, the brilliant Ampere, we can only mention a few of the names which, enrolled upon the lists of fame, have come down to us as household words. In America, to oppose that eminent array of veterans in this particular field of science there was only young Henry, in the Albany Academy. He dared to brave the electric force and demand of it greater energy. Mr. E. N. Dickerson says of him-"He was but a youth and ruddy and fair of countenance, armed only with a simple sling of his own construction and pebbles from the brook of nature, but he was equal to the trained warriors of maturer growth and superior armor, waging war against the Goliath that guarded the unexplored regions of nature's secrets; and like the great king of Israel, after the hunt of the battle was over, he came to be leader of the hosts who once had been tending only a few sheep in the wilderness." THE REED INDUCTION SYSTEM OF TELEGRAPHY. In the operation of telegraph lines the amount of energy required for the transmission of signals is of little account as compared with the importance of securing high speed. Thus, were it possible to increase the commercial capacity of an Atlantic cable ten times by the continuous use of one thousand horse power in current, instead of that of a few cells of battery, it would be an economical step on the company's part to substitute the power plant. The static capacity of long cable, under existing conditions, however, prevents the possibility of transmitting any large quantity of energy or of making variations travel with the desired speed. Some of the most distinguished electricians of the day have endeavored to overcome this difficulty. About twenty years ago Mr. Edison proposed to do away with static capacity almost entirely by breaking up a long line into shorter circuits and employing induction coils; but his system was confined to a dot and space code, and the FIGS. 1 AND 2. action of the armature was unreliable. Prof. S. P. Thompson's method of transmitting a current the whole length of the line and then overcoming static retardation distributively, is still fresh in the minds of those who listened to his paper at the recent Electrical Congress or read the published reports of the proceedings; but while furnishing valuable food for 1. NOTE.-"On the shoulders of young Henry has fallen the mantle of Franklin" were the words of Sir David Brewster. It is true Cox had suggested a chemical telegraph and Hare made many improvements in galvanic apparatus, but no representative of Franklin, in a series of connected experiments, had entered the field of electric sclence in America, until Henry began his researches. 2. See THE ELECTRICAL ENGINEER, Aug. 30, 1892. thought, and much that was theoretically novel and valuable it seems to be open to several practical and mechanical objections. Other inventors have devised ingenious systems to overcome the difficulty but none has yet proved useful in practice. Mr. C. J. Reed, of Philadelphia, has recently worked out a method embodying principles which seem to meet the requirements of the case and in a manner distinctly novel and to all appearances practically available. In his system he employs a true alternating current successively induced in separate metallic circuits which may be entirely insulated from one another. This enables him to use high At electromotive force and transmit large quantities of energy and reduce the static retardation practically to zero. the same time almost any receiving instrument may be used, as it is only necessary to provide it with a local tive impulse until the reverse inductive impulse arrives to means of maintaining the temporary effects of an inducdestroy it. the form of cable employed. In Fig. 1, w and w' are inIn the accompanying illustrations, Figs. 1 and 2 show sulated conductors lying side by side throughout the entire distance between two stations, the conductor w being connected at each end of the line directly to the terminals of the converters B and to the outer metallic coating c, while the conductor w' is connected at both ends directly to the metallic casing. w w' are insulated branch conductors located at stated distances apart, those on the lower side of the drawings connecting the conductor w directly with the outer metallic casing c while those on the upper side and intermediate between those described connect the conductor w' with the metallic casing. I is a metallic sheathing of iron wound in layers around two parallel conductors w and w', constituting an inductive field around them. When an impulse is set up through the primary of, say, the left hand converter B, a secondary or induced impulse will be set up through the conductor w and the first one of the short conductors w returning through the outer casing c, thus inducing in the first section of the conductor w' an impulse which in turn induces in the next succeeding section a corresponding induced impulse; and so on through the series until the final impulse is effected through the conductor w and its connections through the coil of the right hand converter в which in turn induces the working impulse in the receiving instrument. In another form shown in Fig. 2 the continuous conductors are replaced by a series of short conductors w w, the ends of which project past each other in alternating order and are connected to the outer casing c, the parallel or inductive portions of the circuits being surrounded with iron wire, as shown at A, while the intermediate portions between these casings form the conducting parts. In Fig. 3 are shown two main telegraph stations X and Y joined together by an intervening cable consisting of an internal conductor L insulated from a surrounding conduct |