more or less resistance. This motor controller has its moving contacts upon a barrel or cylinder, and geared to this cylinder through the worm-gearing, 31, is a small motor, called a 'pilot motor. A brake is applied to the shaft of this pilot motor through the influence of a spring which operates to press a brake shoe into contact with a disc fixed to the armature shaft. The motor is included in a branch circuit or a local circuit in which are break points controlled by a relay, 43, in circuit between the two motors, M', M2. In the pilot motor circuit is a magnet, 27, and its armature is attached to the brake shoe so that when circuit is complete in the branch containing the pilot motor the brake shoe is withdrawn, and when circuit is broken in the branch the brake shoe is applied by spring pressure as described. In this same branch circuit there is another relay, S. This is connected with the platform switch, P, and this platform switch controls all the motors on all the cars to a certain extent. By putting this switch in any one of three contact positions,-I have only shown one such position,--the pilot motor will run to a point where a certain line of commutation will be perfected by the barrel switch or motor controller. But if, during the run of the pilot motor under the initial or starting movement given it by the motorman, the circuit containing the motors, M', M2, and the magnet, 43, becomes overloaded (that is, if the strength of current exceeds a predetermined safe maximum), the magnet, 43, breaks the branch circuit in which the pilot motor is located, and the magnet, 27, releases the brake shoe, which the spring applies to check as soon as possible the further advance of the pilot motor. The circuit of the pilot motor is broken, and a friction brake is applied to check its momentum as far as possible, and without further increasing the strength of current in the motor circuit. That operation might occur at one motor or another, or upon any one of the three cars. The motorman would not know of it. It is entirely automatic. The motorman receives no warning of it, and he is still free to manipulate his platform switch in spite of anything that the automatic mechanism can do. It is a simple safeguard against the possible erratic action of a motor, either from the slipping of wheels or from the overloading of any particular motor. The motorman's switch is not caught and held, as in Bentley's case, so that the motorman has warning."

In short, the defendant uses a pilot motor to cut out resistance, which it does while the local circuit, in which it is, remains closed, and such pilot motor ceases to cut out resistance when the local circuit is opened, which happens when the strength of the main current becomes too great; and a magnet is used to close and open the circuit, and a brake magnet is used to stop the revolving pilot motor after its circuit has been opened and its motive power taken away, and to release it upon the return of such motive power. Hence the removal of resistance is stopped: (1) By opening the circuit which operates the pilot motor. That is the primary cause. (2) By arresting the inertia of the moving pilot motor. That is an auxiliary cause. But after it has once stopped, the resistance lever is not blocked for the purpose of preventing the removal of resistance. The withdrawal of the brake at such a time would not affect it. The operator is not stopped from turning his lever, nor is his lever obstructed, nor is there any reason for locking it, for he does not have to do in any way with the insertion or removal of resistance, save in the initial act of admitting the main current. Bentley contemplated a controller that should, at the will and at the instance of the operator, cut out or in resistance; and so the magnet applying a brake stopped him at a predetermined point. In the defendant's device. the operator has nothing to do with the matter. To stay or release is, as to him, all alike. He neither inserts nor withdraws resistance, but a circuit normally open cuts out resistance by the operator start

ing; and, when this removal has proceeded sufficiently, a broken circuit stops the removal, aided in stopping acquired motion by a brake released by a magnet. It is true that the operator is just as helpless in the one case as in the other, but in Bentley's patent the conception was to arrest physically the arm of a careless or inefficient operator until such time as there was an automatic adjustment of the current. In the defendant's device the power that removes resistance cannot be improvident, for, beyond the instant when its duty has been nicely and fully effective, it is withdrawn. But compare the disenergizing of the brake magnet so as to let the brake drop on the revolving pilot motor, bereft of its motive power, with complainant's device. Defendant's brake magnet, disenergized, lets the brake on. Bentley's magnet, energized, locks the lever. Defendant's magnet, when energized, draws off the brake. Bentley's magnet, when disenergized, unlocks the lever. A magnet is used for each. In one case a magnet is empowered to stop and lock, and by losing such power it releases; while in the other a magnet, by losing power to hold the brake, lets it on, and by gaining power withdraws it. Hence Bentley uses power in the magnet to stop and hold, and loss of power to release; defendant uses power in the magnet to release, and loss of power to stop; and, while the brake is used to stop acquired motion of the pilot motor, it does not hold nor lock the lever. Its function in this regard will be discussed later. But in one case the hand of the operator is stayed; his machinery is locked; he cannot continue his work of cutting out; in the other the current being once turned on, the cutting in and out is done without reference to the operator.

The foregoing has been by way of description and differentiation, but further discussion and conclusion should await some examination of the prior art.

Letters No. 236,460 dated January 11, 1881, issued to Sawyer, are illustrated by the following diagram:

The throttle magnet, A, in a main circuit, attracts its armature attached to the lever, B, and thereby closes a local circuit, wherein a magnet, J, thereupon attracts its armature attached to a lever, K, whereby resistance is brought in. When there has been proper reduction in the current, the retraction spring attached to lever, B, withdraws it from throttle magnet, A, and opens the local circuit so that the magnet, J, has not power to resist the retraction spring that withdraws lever, K, and removes the resistance. What Sawyer did was to use a magnet in a main circuit to close and open a local circuit, wherein a magnet attracted or released a resistance lever, so as to bring in or cut out resistance as the state of the current required. The magnet, J, alternately holds and releases the lever, K, and admits or suspends the removal of resistance. Bentley interposes a pawl to block the lever, hold it at a standstill, and then release it. But Sawyer taught that a magnet and retracting spring could be used (1) to close and open a circuit; (2) to hold and release the lever that cuts in and out resistance. For what purpose? The specification states:

"Our invention relates to devices for automatically regulating the supply of electricity to a system of electric motors in which it is desired to obtain a uniform speed of rotation, as in autographic telegraph-instruments and other apparatus of precision; and it is obvious, of course, that it may with equal advantage be applied to the regulation of electric currents in any apparatus or for any purpose whatever of this or like nature."

Now, what did Bentley do? Lest the motors in multiple arc, which run more slowly, should absorb an undue portion of the current, and those which run at greater speed be deprived of the necessary amount of current, resulting in injuring or destroying the slow-running motors, he provided a variable resistance in the circuit of each motor, and also a catch or stop which would automatically prevent the removal of too great an amount of resistance from the motor circuit. Sawyer did the same thing, save this: He did not use a catch or stop which blocked the resistance lever, but the magnet acted directly upon the lever, and held or released it. So far as the lever is locked by a pawl held by the magnet, Bentley does something in the way of automatically regulating the resistance lever that Sawyer did not do. If the lever, L', in Bentley's patent, were alternately attracted to and released by the magnet, S, without the interposition of the pawl, G, he, in a degree, would do what Sawyer does, by somewhat different means. But the pawl was better for Bentley's purpose, for he wished to lock the lever so thoroughly that the strength of the operator could not move it. Hence the use of the pawl may be regarded as an advance by Bentley. But the fact reinains that using a magnet and a retracting spring to close and open a circuit, in which a second magnet should hold a resistance lever, or let it operate, is described with great simplicity in the Sawyer letters. The first claim of the Bentley patent and of Sawyer's patent both show (1) an electric motor; (2) a resistance in circuit therewith; (3) mechanism controlling said resistance; (4) an automatic stop for said mechanism in Bentley, and in Sawyer mechanism caus

ing a constant vibration,-that is, intermittent holding and releasing of the lever to cut out and introduce resistance. In the defendant's device the throttle magnet is used, as in Sawyer's patent, to open and close the circuit, upon which the action of the resistance lever is dependent, while the brake magnet, when energized, draws away obstruction from the resistance lever, or allows the brake to return thereto, and is not wanting in strong resemblance to the action. of the magnet, J, and lever, K, as shown by Sawyer. The use of a magnet in a multiple-arc-circuit, to open circuits that energize electromagnets so as to attract levers to introduce or to remove resistances, is shown in Edison letters, No. 264,661, dated September 19, 1882:

The levers, c and d, carry pawls, f and e, which engage ratchet wheels, b, which in turn move an arm, a, which introduces or removes resistance, accordingly as the lever, c, is influenced by the magnet, C, or the lever, d, is attracted by the magnet, D. Here is not a pawl automatically locking the resistance arm or lever, under the influence of a magnet, but a pawl that puts in resistance, and another pawl that removes it, but each pawl is connected with an armature lever, itself immediately dependent upon a magnet that is energized by a primary magnet, E, in the main circuit, opening and breaking the circuit. If the pawl introducing resistance held the ratchet wheel, and thereby the resistance arm, until the current was reduced, it would do precisely what the magnet and pawl effect in Bentley's patent; but instead of this there are two pawls. One automatically brings in the resistance as needed, and one cuts it out as required, and both bring the result. But at least the Edison device shows the use of magnets in main and subsidiary circuits to close circuits so as to bring in and remove resistance, and operating the resistance lever for that purpose. But still the resistance lever is not securely locked, as in Bentley's patent.

The Weston patent, No. 266,239, dated October 17, 1882, is as follows:

It shows a magnet in the main circuit, that, when the current passes a predetermined point, by attracting an armature, d, on a lever, F, through which the circuit passes, brakes the circuit, so that the current passes through a resistance and prevents injury to the motor.

In the patent of Levy, No. 286,834, of October 16, 1883, a throttle

magnet, A, in the main circuit, moves a switch, C, and thereby directs a motor, D, which rotates a controller, so as to bring in or cut out resistance, according to the strength of the current.

The Gale patent, No. 319,573, dated June 9, 1885, relates to lamps

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