Publication: Western Electrician
Chicago, IL, United States
Barclay's Printing Telegraph.
Machine-printing telegraph systems are destined in the opinion of many to play a conspicuous if not a dominant part in the telegraph of the future. The subject was one which attracted attention at the recent International Electrical Congress in St. Louis, and several good papers were read at that time. One of these was by John C. Barclay of New York, in which he described the most fruitful attempts which had been made up to that time in this line of work. It was known at the time that Mr. Barclay himself had near completion a system of this character which was expected to bring forth some new developments. In the latter part of December considerable space was given in the daily newspapers to the remarkable results which had been attained by a series of tests with a system of printing telegraphy invented by Mr. Barclay, who is assistant, general manager of the Western Union Telegraph Company, and which operated with a marked degree of success. At that time a thorough technical description of the apparatus was unavailable. A patent was, however, issued to Mr. Barclay on March 21st, the application having been filed March 1, 1904, for improvements on such a system which in all probability covers the latest developments in the invention upon which he has been working for a considerable time and the success of which was demonstrated some months ago. The following description of the apparatus as embodied in the patent specification will be of interest:
For the transmission of the messages successions of current pulses, are used which are the same in number for all the characters, but vary in length. These pulses are usually, but not necessarily, alternately of opposite directions. For transmitting the characters of the English alphabet there are employed six pulses for each message or character, which enables the operation at will of any one of the 32 magnets, thus permitting the transmission of all the letters of the alphabet and leaving a margin for transmission of punctuation marks and for the operation of spacing, carriage return, shift and paper-feed mechanism. The particular magnet corresponding to each message transmitted is selected by the action of primary and secondary selecting relays, a sunflower and a separator relay.
The invention consists in closing the circuit through contact points of, the selecting relays to the printing magnet selected through a contact of the sunflower itself, in delaying completion of the restoring circuit during the operation of the carriage-return mechanism until the carriage has returned to its starting point, in improved means for operating the spacing mechanism without the operation of the selecting relays and in improved shift mechanism.
Referring to the accompanying diagram, signals incoming over the line wire (5) actuate a main-line relay (4), which is the primary actuating element of the printing telegraph and is the only element of the telegraph in the main-line circuit. This main-line relay may of course be differentially wound to permit of duplex or quadruplex operation the same as an ordinary main-line telegraph relay. The main-line signals for operating this relay may be produced by a hand key or by a keyboard transmitter or by any other suitable means. This particular line relay is of the polar type, being arranged to be actuated by changes of direction of current in the line circuit. Obviously it may be a neutral relay instead, arranged to be operated by rise and fall of the line current. Mainline relay (4) controls two local circuits (6) and (7), connected to opposing contact points of the main-line relay, both of which circuits pass through coils of a neutral relay (8), termed the "separator relay," through opposing coils of a magnet (9), operating escapement mechanism of the sunflower and through a synchronizer magnet (28) to ground at (10). A battery (11) or other suitable source of electrical energy is connected to ground and to the armature of main-line relay. One or the other of circuits (6) and (7) is completed through battery (11), according as the armature of relay (4) is in contact with the right-hand or left-hand contact of the relay. The main-line relay is very rapid in action and operates for each pulse produced in the main line, whether short or long. The senarator relay is more sluggish in action and completes the circuit which it controls only when a long pulse is sent over the line. Being a neutral relay, however, it completes its circuit each time there is a long pulse, whether it be positive or negative. The circuit controlled by separator relay (8) passes from ground at (13) through battery (14), the armature of the separator relay and conductor (15) to a plate (16) of the sunflower, to which the first five contact points (17), (18), (19), (20) and (21) of the sunflower are electrically connected. This sunflower is of the type described in the patent issued to Buckingham, dated August 18, 1895, and consists of contact points (17), (18), (19), (20), (21) and (22), adapted to be actuated successively by teeth of a ratchet wheel (23) during movement of the wheel through the space of one tooth. The ratchet wheel is mounted upon a shaft (24), upon which is also mounted an escapement wheel (25), having three times the number of teeth of ratchet wheel (23) and controlled in its movement by the escapement anchor (26), which is actuated by the armature (27), which is polarized. The coils of magnet (9), through which circuits (6) and (7) pass, being oppositely wound, alternate pulses in these circuits will cause the vibration of the escapement anchor (26), and six such pulses, permitting rotation of escapement wheel (25) through the space of three teeth, will advance ratchet wheel (23) through the space of one tooth, causing contact points (17) to (22) to complete their respective contacts successively and completing one cycle operation of the sunflower. The shaft (24) of the sunflower is driven by any suitable device, such as a spring motor or friction drive, which will permit intermittent motion of the shaft. Magnet (28) beneath the sunflower is a synchronizer magnet 'operating an armature lever (29), having a hook adapted to engage the teeth of ratchet wheel (23).
It was stated above that the metal frame (16) carrying contact points (17) to (21) is connected by conductor (15), passing through contacts of separator relay (8), with battery (14) and thence to ground. These contact points (17) to (21), inclusive, which may be termed "selector contacts," when operated by the movement of ratchet wheel (23) complete circuits successively from the contact points of separator relay (8) through conductors (30) to (34), respectively, leading to the magnets of polar-selecting relays (35), (36), (37), (38) and (39), respectively, and thence through a common-return conductor (40) to ground at (41); but it will be seen that none of these circuits through the magnets of the polar-selecting relays will be closed unless at the instant when any one of those circuits is closed through the sunflower the transmission of a long-pulse through the line has caused the separator relay to complete the circuit through battery (14) to ground at (13). Polar-selecting relays (35) to (39), inclusive, control circuits of secondary selecting relays (42) to (46), respectively, the contact points of which are connected in tandem in the order named, the five series of contact points forming an arithmetical progression. In the present system are illustrated the employment of an alternative and equivalent construction involving the mounting of a number of contact points on the relay armatures so that there is but one relay (43), one relay (44), two relays (45), and four relays (46), each of the relays (44), (45) and (46) having four contact points.
The primary selecting relays (35) to (39), inclusive, each controls a circuit of a corresponding secondary selecting relay or relays. The controlling circuits of these secondary selecting relays (42) to (46), inclusive, are normally broken; but the armatures of the several primary selecting relays are connected by a multiple-current lead (49) to a battery (50) and to ground, and when the magnet of any one polar-selecting relay is energized by a current passing through the sunflower, and its armature is deflected, the polar-selecting relay completes the circuit through the corresponding secondary selecting relay or relays which it controls, thereby operating them. The armatures of the primary or polar-selecting relays (35) to (39) tend to remain in contact with whatever contact point they are in contact with at the time. These relays are provided with a second or restoring circuit (52), passing in series through all of these relays, which circuit when completed by a restoring relay returns the armatures of