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strokes. But it should be borne in mind The wings flap 100 times a minute; that its speed was only four or five miles and when the machine has been susan hour, and the apparatus was crude. pended from a tree-bough, the whole apMoreover, the bird itself weighed twen- paratus apart from the carriage, weighty-one pounds; so it is little wonder that ing 232 pounds, is lifted up bodily into it drooped on the up strokes. The ratio the air and carried forward. It exactly of horse-power to lift was 1 horse-power resembles a giant bird trying to fly. At to 50 pounds. This agrees with the fig- the down stroke, it seems that if the rope ures given by various authorities as that were then cut the powerful sweep of the obtaining among larger birds. In what wings would lift and carry away the enwas called the "hovering lift," 1 horse- tire machine. With 100 flaps per minute, power gave a lift of 10 pounds.
the wings evoked a resistance of about The results were considered so encour- 100 pounds each, and each stroke raised aging that a much larger model was built the machine about 2 feet. Experiments (Fig. 2) and mounted on a special car- showed that a feathered wing made up riage. The new model has a total wing of a number of units exerts greater rearea twenty times the size of its prede- sistance than a simple wing such as that cessor's—that is, about 60 square feet. of an insect or a bat, or the mechanical The entire machine measures 20 feet wings hitherto made for wing-flapping across.
machines. The transmission is by a coned fric- It was clearly seen that the primary tion-clutch and chains in two stages to feathers act as a series of stepped aërothe connecting rod. The crank-throw is planes ;. and altogether a mass of data adjustable for altering the size of the was secured which is about to be emangle of the flap. “Pectoral cords” of bodied by the investigators in a far more elastic are attached to the brackets below ambitious machine than has yet been the wings. These are for storing up en- built. It is proposed to form a small ergy on the up stroke. A gasoline cycle syndicate of men with scientific tastes, to engine of about 3 horse-power is the mo- complete the work and produce a regular tor.
WHEN the snow is whirled
the On a shivering worldWhen the sky has lost its blue
A flower will bloom
In the wintry gloom If love has a smile for you! -F. L. STANTON in Atlanta Constitution.
ROWLAND QUADRUPLEX TELEGRAPH INSTRUMENT. Line-unit on table at right; two correspondence-units on tables to left. This photograph serves to show trans
mitter and home recorder.
HE Rowland system of a perforated or printed tape at the other telegraphy was invented end of the line. The operations conby the late Prof. Henry nected with transmission by this method A. Rowland, of Johns offered too many loopholes for error and Hopkins University, one were too cumbersome to be practical.
of the world's greatest Professor Rowland, in devising his men of attainments in science. In this new system of telegraphy, aimed to acsystem, the alternating current was first complish two great results. First, realizsuccessfully applied to the uses of teleg- ing that the vast network of telegraph raphy.
wires spread over the world was working In their endeavors to improve upon the far below its possible capacity, he wished existing methods of communication and to increase this capacity by multiplexing. increase the capacity of wires, experi- Second, he wished to invent a machine menters have developed apparatus of two that would automatically and directly kinds: the Multiplex, which aimed to record, in page form, printed characters. send many messages simultaneously over In both these fields, little practical adone wire; and the Rapid, which increases vance had been made. As was remarked the speed of the, single transmitter. Of above, two messages each way was the the first kind, however, a Morse appara- limit of the multiplexing systems; and, tus sending two messages each way was although machines had been built to until recently the only one in practical record in printed characters, they were use. The rapid systems have been drop- found impracticable in America after ped, one after another, because their use trial. involved the preparation of a perforated Professor Rowland solved both these tape, which, being shot rapidly through problems with astonishing success. His a transmitter, caused the reproduction of apparatus at its full capacity sends four messages each way over one wire, and the telegraph. The sending or receiving the simple pressure of the proper key at of a telegram is to the average family the sending station is all that is necessary a thing of rare occurrence; but it is to be to have the corresponding character hoped that in the future the reduction in printed at the receiving station. The use cost, owing to the greater ease with of the alternating current is also a tribute which messages may be sent, will proto the originality and foresight of the in- mote among the people a more extended ventor, since it lends itself very readily use of this means of communication. It to the needs of telegraphic communica- would be within the bounds of probability tion. The future will probably see all to say that we may some day even transoverhead wiring banished; and the elec- mit whole letters by telegraph. trical difficulties which are to arise from The Rowland machine, in its present
commercial form, is divided into what are called the line-unit and the correspondence-units. The line-unit has for its function the operation of the line, and contains the necessary apparatus for furnishing the signaling current, impressing the signals, etc. This unit is identical in form at each end of the line. The correspondence units receive and transmit the messages; each consists of a transmitter, a receiver, and a home recorder. The transmitter is a universal typewriter keyboard; the receiver an automatic page-printing machine, which records the message in page form on a telegraph blank, ready for delivery; and the home recorder a printed tape passing along a scale before the eyes of the operator, giving a duplicate of the message sent out. There is another correspondence unit at the other station, which is the twin of the one just referred to. These two send to each other, and receive from each other, the signals going
continually over the line, which are rethe placing of wires underground and in corded exactly as a typewriter records its cables will be more easily overcome than letters upon a page.
The operator, by with a direct current.
the depression of certain keys, lines and It is hard to predict the far-reaching spaces as though he were operating an effect that the Rowland system will have ordinary typewriter. A red light takes on the telegraphic communication of the the place of the typewriter bell, the carworld. The messages, by automatic rep- riage being backed and the light extinetition, may be transmitted thousands of guished by the pressure of a key. When miles; and this advantage, combined with the end of a message is reached, a quickthose of cheapened service and greater shifting device throws in a blank section facility of transmission, will undoubtedly of the paper before the next message is put into direct communication great begun. In fact, the operator's knowlworld centers which have hitherto com- edge of his printer's movements is so acmunicated with one another only by long curate that tabulation may be done. Specand circuitous routes. It has also been imens of this character of work have been found that the system, when once well transmitted over actual lines 500 miles in established, has partially superseded the length. These correspondence-units are mails and the telephone. It will be neces- instantly and easily detachable, and if one sary, however, to educate the public to a gets out of order another can immedirealization of the latent possibilities of ately be substituted for it.
To understand the system in all its de- Every revolution of the brush will have tails, requires considerable study. The this same effect, provided the flow of curmost that can be done in an article of so rent through the coils is always in the limited a scope as this, is to show the same direction. But if the particular imbare principle upon which the machine pulse of current received by this relay is works—the application of the alternating reversed in direction, the magnetic effect current to the sending of signals.
produced in the coils will be opposite to The figure represents the end view of a that in the case referred to above, and the commutator which has a brush traveling over its surface. This brush has a wire running to a source of alternating current. The segments of the commutator have relays connected to them, one of which is shown in the diagram. It will be seen that as the brush makes contact with the segment connected to the coils of any particular relay, the current can pass through the coils of that relay and back to its source. Suppose the motion of the brush and the alternations of the current to be so adjusted to each other
END VIEW OF COMMUTATOR. that the current will change in direction
Showing connections whereby circuits are opened and each time the brush passes from one seg
closed in sending messages. ment to another. This will cause each pair of coils to get a momentary flow of tongue will be thrown against its "front current in one direction or the other ac- stop," the contact-point b. If the mechcording to the adjustments
. Suppose the anism shown in the diagram is placed at relay shown receives an "impulse" of one end of a telegraph wire, and the imcurrent in the direction indicated by the pulses of alternating current supplied to arrow. This current will cause mag- it are controlled from the other end, an netism to be produced in the coils, which operator might throw the tongues to magnetism, we shall say, throws the their front stops at will boy reversing the tongue t against the contact point a. proper impulses of the alternating cur
rent. Thus, these tongues might be used erator has the use of the line at rapidly as little switches to complete the circuit recurring intervals. These intervals octhrough electrical mechanism that would cur at each revolution and are 2-7ths of a perform some desired operation, such as second apart, the machine making 3/2 printing a character or backing a car- revolutions per second. The line is duriage. This is actually done in the Row- plexed in the usual manner by the use of land machine. The above case is ideal, polarized relays and an artificial line, so however, and is varied considerably in that the four messages being received at practice. Mechanism is used whereby each station do not interfere to any extent
eleven relays and segments serve to send whatever with the four messages that are the 51 signals from each keyboard, being sent at the same time. whereas the illustrated case would re- The machines are very interesting from quire one relay and segment for each an electrical standpoint. One very striksignal.
ing instance of the delicacy of the reguThe multiplexing is accomplished in lating devices may be referred to here. the following manner. The commutator The Rowland is what is called a synthat receives the impulses from the line chronous system ; that is, the moving is divided into quadrants, each contain- parts at the two stations must be kept ing the segments that are connected to rotating at exactly the same rate of the relays controlling one particular speed. This synchronism is maintained printer. These relays receive impulses with such accuracy, by electrical means, only for the time during which the re- between the two line-unit motors, each volving brush is passing over their own running at 1,960 revolutions per minute, segments. The keyboard of the operator that the variation in speed does not who controls this printer at the sending amount to 1-6 of a revolution for days station, is automatically unlocked at the at a time; this with the motors hundreds proper time to enable him to reverse the of miles apart. impulses of current received by the relays The Rowland machines have been opcontrolling his printer. Thus each op- erated successfully both in this country