Almon brown strowger
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| ALMON BROWN STROWGER
Commentsd and Compilation by Bob Stoffels February, 2003 The story of Almon Brown Strowger, the man who invented the dial telephone system, has been repeated many times over the years by telecommunications historians. In general the stories agree; in detail they differ significantly. What follows are comments, and then excerpts from articles, publications, letters and patents that tell this story. We must point out that some of the published “details” are clearly speculations. For instance, do we know what sort of an overcoat was worn by Mr. Strowger on the day he conceived of the step-by-step switch? STROWGER THE MANHe was a wiry little guy; tipped the scales at about 110 pounds. Had bushy white side whiskers. Inventive. Ingenious. And short of temper. Likely, were it not for this temper, the step-by-step switch that bears his name would never have been invented. His early life was rather unremarkable. As we shall see, he served as a school teacher, and then as principal. In later years he became an undertaker, and it is here that our story begins. Automatic InventorJ. Hartwell Jones Telephony magazine October 15, 1949 In many ways Almon Brown Strowger’s invention was more remarkable than that of the immortal Bell. The idea of transmitting speech over wires was an old one when Bell was experimenting with this “harmonic telegraph.” A fortunate incident set Bell on the right track. By contrast, this man was a pioneer in uncharted seas. He set his mind to a task and devised a mechanism that had no predecessors. His original idea embodied the principles that largely are in use today. The story of Strowger is a fascinating one which should be better known by those in the industry today. His ancestors were from Suffolk county, England. Strowger himself was born in Penfield, N.Y., on October 19, 1839. He was of a large family with six brothers, one of whom died young. One became an Episcopalian clergyman, one a lawyer, another a surveyor, and two were farmers. These boys had five sisters. On his 22nd birthday, Almon Brown Strowger enlisted in Co. A., 8th New York Cavalry, then recruiting in Rochester. He received a commission as second lieutenant in this regiment in the fall of 1864, and on December 8 of that year was honorably discharged. About two months later he married Rosaltha M. Clarke. Children of this marriage were Harriet Malvine and Mary Rosaltha. The second daughter, now Mrs. Mary R. Doan, is presently living in Stockton, California. Strowger’s occupation as a young man was teaching school. He was principal of the Penfield school which he had attended as a pupil, and taught in schools at Villa Ridge and Anna, Ill., North Lansing, Michigan, and in Kansas. He lived in Topeka, Kansas, between 1883 and 1886. Strowger had bought an undertaking establishment, and as was the common practice, was living at the same location. City directories for that period listed him: “Strowger, A.B., undertaker, 610 Kansas Ave., North Topeka, res. Same. Wife: E.A. Strowger.” His first wife had died prior to this time and he was then married to a former “Anna Condon,” according to the recollection of a surviving niece. Whether she died or was divorced is uncertain, but on March 4, 1886, he married Alice Marie Hill. The sole child of this marriage was a son, John Almon, born about two years later when his father was 49 years old. This only son was killed in a sawmill explosion near Tampa, Florida, in 1923. Strowger sold his business in Topeka, and moved to Kansas City, Missouri, continuing in his profession of undertaker. It was there that he became interested in telephone service. How Strowger conceived the idea of an automatic telephone system to replace switchboard operators when the telephone itself was little more than 10 years old is an example of the manner in which the events of everyday living can drive the human brain to new heights of scientific discovery and invention. The story is told that Strowger went to his office one morning, hung his Prince Albert coat on the wall, secured the Kansas City morning paper, sat down in his chair, placed his feet upon his desk, and began to read. Suddenly his attention was attracted to an item of news, which told him that a friend had died. To his astonishment and amazement he read that the burial was to be handled by a competitor. When he saw this, he jumped to the conclusion that his friends had tried to reach him by telephone, but the operator had undoubtedly given the call to his competitor. As a result he had lost the business. Immediately, so it is told, he flew into a rage. His eye fell upon the telephone on the wall a few feet distant; he crossed over to the instrument, rang the bell impatiently, and when the operator answered spoke to her angrily. The operator’s protestation that she was entirely innocent did not satisfy him, and slamming the receiver back onto the hook, he impatiently walked the floor. Suddenly the thought came to him; why not build a telephone system that will not require an operator. “Surely,” he must have reasoned, “just so long as there are human operators with their human frailties, there will be human mistakes.” He began to ponder over this, and the more he thought about it the more he resolved that he could and would build such a telephone system. . . . One day sitting at his desk and thinking about the matter, he pulled open a drawer and took out a round cardboard box holding a dozen paper collars. He emptied it of its contents, and from the desk in front of him picked up a paper of pins. One by one he stuck the pins from the outside of the box toward the center, until he had 10 rows of 10 each. These 100 pin points represented 100 subscribers’ lines. Then he took a lead pencil and held it out to the center of the box in front of those pins, and muse to himself somewhat as follows: “It should be possible for me to get an electrician to introduce some magnets and other equipment in such a manner that if I wish to connect with No. 75, it would automatically take hold of this lead pencil and lift it up to the proper level, the seventh, and move it to the fifth pin point making a contact, thus connecting with 75. . . . So Strowger worked toward the realization of his vision, just as Bell had done 13 or 14 years before. On March 12, 1889, he filed an application with the U.S. Patent Office for an “Automatic Telephone Exchange.” Patent No. 447,918 was granted to Almon B. Strowger almost two years later, on March 10, 1891. . . . On February 19, 1892, Strowger filed for another patent with further refinements on his original idea. On the same date, he and his nephew, Walter S. Strowger, who was in on the founding of the company, filed for a patent on a “Combined Indicating Electric Switch and Current Reverser.” Both applications were filed by Strowger’s attorney, Oscar Snell. The first was granted on November 29, 1892, and the second on March 7, 1893. . . . Strowger’s health began to fail in the late ‘90s while he was in Chicago. He had a nurse named Susan Belianger, whom he married. The records are not clear whether this was his fourth or fifth wife. One of Strowger’s sisters had gone to St. Petersburg, Florida, for her health, and her daughter was living there. This may have influenced him to choose this particular spot in his search for a milder climate. Some time in 1897 or 1898 he moved to the then-small Florida town with his last wife and son John, who couldn’t have been more than about 10 at the time. Strowger, at this time of life, is described by old residents who knew him well as “a rather energetic, nervous little man, weighing about 110 pounds, with a face framed in white whiskers.” It is said that he had a “jolly, fat little wife.” His son John probably would not have agreed with this, because he left home due to difference with his step-mother. Later, in his father’s will, reference was made to the appointment of a guardian for “my son John Almon.” By the spring of 1899, Strowger had become very much enthused about the growth of St. Petersburg which was then a struggling little town of about 1,200 population. He bought three lots for $3,250 and built a two-story frame building, with stores on the ground floor. He lived for a time on the second floor, as did one of his tenants who operated a drug store in the building. He purchased two other lots for $1,950, on which he erected another two-story frame building that is still in use today. He also bought and moved into a frame house that was his home until his death. It remains relatively unchanged in external appearance. Strowger is said to have been quick of movement – and quick of temper. He did his own planning, superintended his own construction work and personally took care of all his properties until the summer of 1991 when his eyesight failed and he had to give up his active work. R. H. Sumner, then a young man in his early twenties, became a good friend of Strowger and used to read to him while his eyesight was failing. Sumner, who died this year, later became one of the founders of St. Petersburg’s first telephone company. Sumner has given us this picture of Strowger in the sunset of his life: “During the few years he lived in St. Petersburg, he was an ardent booster for the city and was very active in all political and civic affairs. He was not known locally as an inventor but rather as an investor. He gave generously of his time and money when the occasion demanded. Strowger became a familiar figure on the unpaved streets of St. Petersburg as he drove a pure white horse and a shiny black buggy, and he was always on the move. He was a very outspoken, high tempered man and if he didn’t like the way the city was doing certain things he did not mind telling somebody how it should be done and oftimes would take over and do it himself.” One of Strowger’s nieces, Mrs. Frank Singlehurst, who was living in St. Petersburg at the time of her uncle’s death, says that he died of pernicious anemia. The date is established as May 26, 1902. Buried for 47 years under a simple marker indicating only his war service, Strowger’s grave this month was dignified by the addition of a bronze plaque. On the 110th anniversary of his birth, the Penninsular Telephone Co. and others, gave proper recognition to this great inventor whose contribution has meant so much not only to the Independent industry, where it originated, but to the entire telephone field. BUSINESS PLANInventions do not succeed by themselves alone. There must be organization, skill in finance, production and marketing, motivation and leadership of people, imagination and faith, and hard work. The Strowger Switch is a case in point. Remarkable though the invention was, the old saying “build a better mousetrap and the world will beat a path to your door,” is simply not true. Interestingly, Almon Strowger was not (at least initially) excited about any sort of a business plan. As we will see, even when there was an interested party, and that party invited Strowger to Chicago, and even paid his way, Strowger declined. The man who was interested, and did push the application of the invention was one Joseph Harris, a traveling salesman. Through the years this man worked tirelessly to promote the Switch. He established factories, arranged for field trials, and saw to the improvement of the resultant products. Here is his story. Communications PioneerJoseph Harris GTE publication Written approximately 1920
When we got the switches we were really no better off than before because we had no telephones. I was personally acquainted with Mr. Charles Wilson then General Manager of the Chicago Telephone Company, and induced him to look at the switch. After examining it and finding that it would require five wires between each telephone and the switch, he said to me that it was impracticable, and undertook to dissuade me from going further. I told him I was determined to go along with it, if possible reducing the number of wires required, and finally persuaded him to loan me three telephones. We then set up a connection with three telephones, using instead of a dial a push button device at the telephone. The maximum capacity of a system at that time was 99 numbers, and in order to get 99, you had to push the button 13 times, or if it was 89, you would have to push it 17 times but, it worked, and we knew that we had the germ of an automatic telephone system. Late in 1891 we, incorporated the Strowger Automatic Telephone Exchange with an authorized capital stock of $5,000,000. We had no money, and in the absence of Blue Sky Laws in those days, we sold stock of a par value of $100 per share for $10 per share. Mr. Strowger’s estimate of the cost of perfecting and completing the apparatus for practical commercial use was $50,000. We set out to raise this amount of money by the sale of stock on the basis above stated. The officers of the Strowger Automatic Telephone Exchange at that time were M. A. Meyer, President; A. B. Strowger, Vice-President; Joseph Harris, Secretary and Treasurer. Mr. Strowger was paid a salary of $100 per month, the other officers of the company drew no salary. From the sale of, stock, on the above basis, we raised $50,000 but had scarcely scratched the surface of the proposition until this money was practically exhausted. We set out to sell more stock at ten cents on the dollar. We had an agent traveling selling stock and in 1891 he drifted into Baltimore and interested a number of people to the extent that they sent an engineer to Chicago to investigate. The man they sent was Alexander E. Keith, who was then with the Brush Electric Light Company. He had previously had a number of years experience in the installation of telephones for the Bell system and prior to that was with the company installing telephones, electric lights, paper mills, etc. in South America. Mr. Keith came to Chicago, looked over the device, told us we had something that might become all we thought it would, but it would require a great deal of time and money. On the strength of Mr. Keith’s report to his principals in Baltimore, a considerable amount of stock was sold at $10 per share and we were able to exist. It afterwards occurred to me that Mr. Keith would be a valuable acquisition for our organization. I made an appointment to meet him in Washington and finally persuaded him to join our forces, and bring his family to Chicago. He has been associated with the automatic telephone ever since, first as chief engineer of the Strowger Company and when it was taken over by Automatic Electric Company was chief engineer for that company and now is Vice President in charge of development and research work for Automatic Electric Company, and has completed his thirtieth year in continuous service in the development of automatic telephone equipment. After Mr. Keith’s arrival in Chicago, we continued the model work under his direction. When these were made so they would operate, we contracted with the Columbia Novelty Works of Chicago to manufacture 200 switches with the idea of making an installation for public use, thus better demonstrating its utility. In pursuance of this idea, we obtained a franchise at La Porte, Indiana, and in 1892 installed a 99 line system in the town. Meantime we needed more money. When the Strowger Automatic Telephone Exchange was incorporated and the stock issued, A. B. and Walter Strowger received a million dollars worth of stock. In attempting to sell our stock for $10 per share we very soon found that the Strowgers were offering their stock as low as two or three dollars a share, apparently anything to get some money out of it, regardless of its effect on the company. This embarrassing situation continued for several years and was only one of the difficulties we encountered in financing. When the La Porte installation was completed, we were notified by the Bell Company from Boston, that if we continued to give telephone service they would sue us for infringement and the users were notified that if they continued to use the service they would be sued as infringers and cited before the United States Court at Indianapolis. We wrote the Bell Company in Boston that the plant was installed at La Porte for experimental purposes only in an effort to develop an automatic telephone service which would please the public. We further notified them that no charge for service was being made and none was made. Later on we sold the plant complete to some La Porte people who continued the service and later began charging rentals. The money realized from the sale of the La Porte property together with what little we could get from the sale of stock in competition with the Strowgers, enabled us to carry on in a very modest way, because it was very difficult to sell stock to the public in view of the threatening patent litigation and it really was only through personal friendship and confidence in us of those who knew us, that we were able to raise any money in this way. During all this time, up to 1899, the Bell Company was prosecuting suits against infringers of the transmitters and other devices and not until 1899 was the transmitter suit decided adversely to the Bell Company in the United States Court at Boston. In the meantime, the Independent telephone movement was gaining ground and it was common practice for the Bell Company, until the adverse decision above referred to, to serve notice on owners of operating plants and also patrons of those plants, both through publication in local newspapers and by circulars mailed direct, that infringers of patents (which would usually be specifically mentioned in these notices) would be prosecuted. It was generally understood not only among telephone people and users of telephone apparatus, but the public generally felt that the Bell Company was threatening suit on account of its patents. It was under all of these adverse conditions that we financed the Strowger Company as best we could. Meantime, we had sold rights in certain territory and our licensees organized a few small companies and contracted with the Strowger Company for. equipment. Installations were made in this way at Michigan City, Ind., Auburn and Rockaway, N. Y., and several other smaller places in New York and Pennsylvania. The territorial rights were usually sold to groups of local people, they agreeing to pay us so much royalty for each line installed and a minimum number of lines each year were to be installed. On failure to install such minimum number of lines, and the payment of royalty, the territory would revert back to us. The larger installations made during this period was one at Albuquerque, N. M., 400 lines in 1895, and one in Augusta, Ga., in 1896-97. The failure of licensees to install the required number of lines and pay royalties was usually brought about by their inability to finance the construction of plants, largely because of the campaign of intimidation carried on by the Bell Company, and after paying royalties for a year or two they would forfeit the territory and we would be obliged to sell it again or it would remain open. It really was a story of continuous performances in many of these territories. The last of these territorial rights outstanding was taken up in January, 1903. This included the states of New York, Pennsylvania and the Dominion of Canada. That was the only territory except Massachusetts and Rhode Island, which had not previously lapsed. The next installations of consequence were in New Bedford, Mass., in 1900 and Fall River, Mass., in 1901. By the first of 1897, the Strowger Company had gotten into such financial straits, stretched its credit so far that is, whatever credit it had, that it was absolutely impossible for it to go any further. At this time, a group of people from Washington came along, negotiated for the rights under the Strowger patents with the result that a contract was entered into by the terms of which a new company was to be formed, the foreign and domestic rights taken over by it on the agreement of the new company to pay a fixed sum at stated intervals, plus royalties on the amount of business done. Under this arrangement the factory was moved to Baltimore. The deal when made looked like a favorable one. At any rate it was the best and only thing we could do at the time. This arrangement continued for about five years. The Washington company, which was called the Automatic Telephone Manufacturing Company Ltd. of Washington, failed to pay the stated sums of money and royalties and the Strowger company tried to have the contract annulled. This resulted in litigation, in which the Washington Company secured an injunction restraining the Strowger Company from manufacturing and selling apparatus. Prior to the purchase of the rights by the Washington Company the Strowger Company had sold rights to a Massachusetts group for Massachusetts and some adjacent territory. That group was known as the Eastern Automatic Telephone Company and had kept its rights alive. After the transfer of the assets to the Washington Company it ordered equipment. from the Strowger Company for New Bedford. The Washington Company refused to fill the order for New Bedford. The Strowger Company was obliged to furnish this equipment under its license contract, as it was receiving royalties from the Eastern Company. It made a contract with the National Machine and Tool Company of Boston, Mass., furnished it with samples, with which the latter Company made the equipment for New Bedford. Mr. Martin left the employ of the Strowger Company, went to work for the Eastern Company and installed New Bedford. After making the contract with the National Machine and Tool Company the Washington Company secured an injunction to restrain us from manufacturing. In 1899 we were still having trouble with the Washington Company, which was doing nothing either in the way of making payments or manufacturing equipment. Meantime, I was in negotiation with the Washington Company trying to make another contract and get matters cleaned up. I was in Baltimore and wired Mr. Keith to come over, which he did and it was agreed between us that Mr. Keith was to go to the factory in Baltimore, arrange to have the machinery, tools and dies packed for shipment, loaded on cars and get it out as quickly as possible. Mr. T. E. Meyer, one of our men who had been transferred to the Baltimore Company, and who is still in our employ, entered heartily into this and got some of the boys who were with him to dismantle the factory, ship the machinery, etc. The Superintendent of the factory was a man named Ford, and Mr. Keith’s job was to keep him away from the factory while things were being packed and carted out. This was done, and in thirty-six hours all of the factory equipment, except materials, was packed, carted, put on cars, which were sealed, and started for Chicago. This will give you an idea of the magnitude of the Strowger factory at that time. This equipment arrived in Chicago and was installed in our factory on Jefferson Street, where we did enough manufacturing of small parts, etc., to justify its being kept alive. . . . THE STROWGER SWITCH Today we might call it a “beta” test. That is, put your invention to use in a location where it can be studied, and used under actual conditions. In the late 1880s there was no such term, but it was nevertheless essential that the invention – any invention – be trialed in the field. The first application of the Strowger Switch took place in La Porte, Indiana. The switch used differed somewhat from the invention described in the original patent application, but in concept it was the same. Automatic InventorJ. Hartwell Jones Telephony magazine October 15, 1949 . . . (E)vents were shaping up in the progressive little city of La Porte, Indiana, that were to create for it a most unusual distinction. About 1888 or 1889 the Cushman Telephone Co. established an exchange at La Porte, one, probably the Bell, having been operated a short time before. In 1890, suit for patent infringement was brought by the Bell company against all subscribers in La Porte, before Judge Henry W. Blodgett, Chicago, who ordered all the telephones to be burned. W. W. Hans, the Cushman manager, shipped them to Chicago for the purpose. . . . The next part of this story can be told best by direct quotation from the reverse of a beautifully engraved invitation: “The City of La Porte, Ind., situated 60 miles from Chicago, on the Lake Shore and Michigan R. R. , is the first city in the world to adopt an Automatic Telephone Exchange. “Under a franchise granted July 18, 1892, by the city of La Porte to the Strowger Automatic Telephone Exchange, a system has been completed under its patents and is now in operation. “This invitation is issued for the purpose of convincing by a practical demonstration to the electrical experts and to the scientific world, that through this system a degree of perfection has been reached that will be of great commercial value and enhance many fold the uses of the telephone. We will demonstrate that this system entirely obviates the many annoyances to which subscribers are at present subjected, besides being much more economical than the system now in use. “A special train for La Porte will leave the Lake Shore & Michigan Southern depot (Van Buren Street) Thursday, Nov. 3, at 10:30 a.m., returning to Chicago at 5:45 p.m. “Lunch and refreshments will be served on the train. Address direct reply to J. Harris, secretary.” The demonstration on Nov. 3, 1892, was less than four months after their franchise was granted, so certainly the equipment couldn’t have been working for long before hand. On the following day the Daily Herald of La Porte gave the event a fine writeup of several columns, including drawings of a switch and the switchroom. Fifty of 60 persons were on the train, including bankers, journalists and railroad men. One man was from Paris, France, two Canadians were present, and two Russians – the consul and a commissioner. The train was met by Mayor Scott and the city band, and the visitors escorted to the exchange by them. Subscribers had been forewarned of the big event and were asked to “answer their telephones very promptly on calls between 12:30 and 4 p.m.” When Strowger spoke he said that under his system “the telephone girl would have to go, but she would only be following in the footsteps of the messenger boy whose services were dispensed with by the invention of the telephone.” He revealed that another new system was under construction at Fort Sheridan, Ill., which was to be in operation within a few weeks. In speaking of the performance of the exchange, this paper says “If an error has been made, the person calling may be sure he, and not the machine, is at fault. Machines make no mistakes.” The original La Porte installation was a “five-wire” system, with five wires from the exchange to each telephone. The instruments were equipped with push buttons. If any subscriber desired to call No. 75, for example, he had to push the button representing “tens” seven times and button representing the units” five times or a total of 12 operations of the buttons. Then by turning his generator he could ring the called party. However, the equipment worked successfully and people liked it. THE INVENTIONDetails fade with time. Most certainly Almon B. Strowger filed his landmark patent application on March 12, 1889, and certainly the first application of the “Strowger Switch” was in La Porte, Indiana, in November, 1992. But beyond this we cannot be sure. The patent drawing shows the switch being operated with five wires and four push-buttons: the first button energized the switch in the vertical direction, and represented the hundreds digit. The second button rotated the shaft in the center of the circular switch, but ten steps at a time. This represented the tens digit. The third button rotated the shaft only one step at a time. This represented the units digit. The fourth button energized the release function; it returned the switch to the normal, starting, position. One reference suggests that there was a fifth button, the ring button, which had to be pressed to ring the called party’s phone. As might be expected, there was a wire tied to each of these buttons, (making four) and then there was at least one additional wires, tied to the wiper of the switch, (it amounted to what we would call L1) making five. Yet another requirement was for ringing. No mention is made of this. And finally, provisions had to be made for ground. The original La Porte installation utilized a five-wire system, but because the total number of lines was less than 100, there was no reason to utilize (or even have) the hundreds button, or, for that matter, more than one level of contacts. Following are various descriptions of the Strowger Switch: Automatic InventorBy J. Hartwell Jones Telephony magazine October 15, 1949
Bell Telephone Laboratories, Incorporated Reprinted from Bell Laboratories Record, March, 1953 . . . Strowger filed his patent application on March 12, 1889, and it was issued on March 10, 1891 as patent No. 447,918. The mechanism of Strowger’s patent is shown in the figure. While this particular arrangement was never used commercially, it illustrates the inventor’s original ideas. As may be seen, an individual switch was required at the central office for each subscriber line. The switch consisted essentially of a hollow cylinder with a shaft capable of both vertical and rotary motion. This shaft carried a wiper arm capable of wiping over all the horizontal rows of contacts on the inside of the cylinder. All of the subscriber lines were mulipled to the rows of terminals around the cylinder of every switch, while one of the subscriber lines was connected to the wiper of each switch. Strowger did not specify in his patent the maximum number of lines which could be terminated in his switch, but in a circular issued in April, 1891, he claimed that it would “connect telephones in a system from two to ten thousand.” In describing its method of operation, however, most writers have assumed ten horizontal rows of 100 contacts each. (Even this number would have required a switch prohibitive in size and cost.) The vertical and rotary motions of the shaft were controlled by electromagnets actuated by impulses sent from the subscriber station. Four push buttons on the subscriber telephone box each controlled a wire to the central office, while the fifth wire was for talking. To call the number 315, Strowger states in his patent, the subscriber pressed his “hundreds” button (G) three times, thus lifting the shaft of his switch three notches and bringing the wiper opposite the third row of terminals. He then pressed his “tens” button (H) once, which gave a single rotation to a 10-toothed ratchet wheel (E) attached to the shaft and moved the wiper arm to 310. Pressing the “units” button (I) five times operated a 100-toothed ratchet wheel (E) attached to the shaft and moved the wiper arm five more points to 315. Ringing was done with a magneto or battery. When through talking the calling subscriber pressed the (P) button, which energized the release magnets and brought the shaft and wiper arm back to their normal positions. The use of five wires and ground was, of course, an impractical feature, but Strowger planned to later reduce the number of wires. A heavy battery was to be employed at each sub-station for operating the central office switch. There was no provision against the calling subscriber being connected to a busy line. . . . On November 3, 1892, the first Strowger exchange was opened for public service at La Porte, Indiana, with about seventy-five subscribers. . . . Since this system was designed for less than 100 lines, there was no need for a switch with a two-way movement, and a flat rubber disc type of switch was employed, with but one (rotary) movement for the wiper arm and one circular row of contacts. There were still five line wires, as in Strowger’s patent, and each telephone was equipped with four push buttons, although the hundreds button was not used. The battery for operating the switches was now located at the central office. . . . Almon B. Strowgerby Arthur Bessey Smith Automatic Electric publication May 1, 1952
Chicago 7, Illinois Author unknown Written approximately 1954 Key element in the switching of a telephone call by means of the Strowger Automatic system is the “Strowger Switch.” In its basic form each Strowger switch consists of the following elements: A vertical shaft carrying a set of connecting fingers known as “wipers.” A “contact bank” consisting of 100 sets of metal contacts stacked in 10 curved rows or arcs, each row having 10 sets of contacts. Each set of contacts represents the terminals of one line or trunk. An electro-mechanical device capable of raising the shaft vertically any number of steps from one to 10, and then rotating the shaft horizontally any number of steps from one to 10, thus causing the wipers to connect to one particular set of contacts in the bank. A release mechanism by which the shaft may be permitted to drop back to its original position. This basic Strowger mechanism may be designed and wired to serve any one of the following switching functions: As a Linefinder: In this case the bank contacts are the terminals of subscribers’ lines, and the switch operates automatically when the calling subscriber lifts his handset to make a call. The shaft and wipers lift and rotate until the wipers come to rest on the terminals of the calling line. This action takes place in a fraction of a second – before the subscriber has a chance to operate his dial. As a Selector: In this case, the vertical motion is controlled by the dial at the calling station, and the rotary motion, which is completely automatic, serves to select an idle trunk to the group of lines represented by the particular figure dialed. As a Connector: this switch is the last in the train of switches used in setting up a connection, and both vertical and rotary motions are controlled by operation of the dial. After the connector reaches the terminals of the called lines, it tests that line for busy condition. If the called line is busy, the switch returns “busy tone” to the calling station. If the called line is idle, the switch sends out a ringing signal, and when the called station answers, the two stations are connected for conversation. When the handsets are replaced after conversation, the shafts and wipers of all switches in the train drop back to their original positions; and the same switches are then available to other subscribers. MEMORIALAlmon Brown Strowger died in St. Petersburg, Florida, May 26, 1902. He was laid to rest in Greenwood cemetery, 9th Street South, 11th Ave. South, in the historic Roser Park neighborhood. At the time of the burial Greenwood cemetery was outside the city limits of the still-young city. There is a simple white stone marking the grave, that says: Lieut. A.B. Strowger, Co. A, 8 NY Cav. On the 110th anniversary of his birth, the Penninsular Telephone Co. and others gave proper recognition to Strowger by installing a plaque that read: Here rests the remains of ALMON BROWN STROWGER 1839 – 1902 INVENTOR & PIONEER whose dream of better telephone service inspired him to invent in 1889 the first practical automatic telephone system. This plaque placed here in his honor on the 110th anniversary of his birth by grateful members of the telephone industry October 19, 1949 PICTURE CAPTIONS left: Almon B Strowger, inventor of the first automatic telephone switching system . right: Joseph Harris, entrepreneur and business man who carried the system forward. upper left: Replica of the first Strowger Switch invented by Almon B. Strowger lower left: Switch used in the La Porte, Indiana, telephone system. right: A “modern day” Selector switch, embodying the Strowger principle Original patent diagram of the Strowger Switch, March 10, 1891 4. Patent drawing of an 1899 Strowger Switch 5. Head stone and memorial plaque on grave of Almon B. Strowger, Greenwood Cemetery, St. Petersburg, Florida Directory: wp-content -> uploads -> 2017 2017 -> Leadership ohio 2017 -> Ascension Lutheran Church Counter’s Schedule January to December 2017 2017 -> Board of directors juanita Gibbons-Delaney, mha, rn president 390 Stone Castle Pass Atlanta, ga 30331 2017 -> Military History Anniversaries 16 thru 31 January Events in History over the next 15 day period that had U. S. military involvement or impacted in some way on U. S military operations or American interests 2017 -> The Or Shalom Cemetery Community Teaching on related issues of Integral 2017 -> Ford onthult samenwerking met Amazon Alexa en introduceert nieuwe navigatiemogelijkheden van Ford sync® 3 met Applink 2017 -> Start Learn and Increase gk. Question (1) Name the term used for talking on internet with the help of text messege? 2017 -> Press release from 24. 03. 2017 From a Charleston Car to a Mafia Sedan 2017 -> Tage Participants 2017 -> Citi Chicago Debate Championship Varsity and jv previews Download 62.2 Kb. Share with your friends:
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