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alternating current Alternating Current Machine amperes apparatus arma armature coils arrangement axis bars battery binding-posts Brush machine Bunsen cells candles Carcel burners centimetres chine collector cylinder commutator connected construction continuous current convolutions copper curve diagram diameter direction dynamo dynamo-electric machines Edison electric light electro-magnets electromotive force external circuit fastened field magnets galvanometer galvanoplastic Gramme machine grooves heat horse-power induced currents induction intensity iron core iron ring kilogrammes lamps large machines lines of force magnet poles magnetic field magneto-electric machine main circuit metal metres millimetres Ohm's law ohms opposite pair of bobbins parallel permanent magnets pieces placed plates points polar extensions pole-pieces portion position produced pulley radial rent resistance revolving segments shaft shown in Fig side Siemens & Halske Siemens machine soft iron solenoid space spools springs strength of current tension tion ture weight winding wire wire coils wound
Page 137 - If now, while the circuit of the armature remains completed, the rheomotor be removed from the electro-magnet, on causing the armature to revolve, however rapidly, it will be found by the interposition of a galvanometer, or any other test, that but very slight effects take place. Though these...
Page 136 - I have employed. The construction, it will be seen, is the same as that of the electro-magnetic part of Mr. Wilde's machine. The core of the electro-magnet is formed of a plate of soft iron 15 inches in length and ^ an inch in breadth, bent at the middle of its length into a horseshoe form.
Page 139 - On bringing the primary coil of an inductorium (Ruhmkorff's coil) into the circuit formed by connecting the coils of the electro-magnet and rotating armature, no spark occurs in the secondary coil. On account of the great resistance of the circuit, which now also includes the primary coil of the inductorium, the current is not in sufficient quantity to produce any noticeable inductive effect.
Page 139 - A very remarkable increase of all the effects, accompanied by a diminution in the resistance of the machine, is observed when a cross wire is placed so as to divert a great portion of the current from the electro-magnet.
Page 137 - ... 0067 in diameter, by its making a powerful electromagnet, by its decomposing water, and by other tests. The explanation of these effects is as follows: — The electromagnet always retains a slight residual magnetism, and is therefore in the condition of a weak permanent magnet ; the motion of the armature occasions feeble currents in alternate directions in the coils thereof, which, after being reduced to the same direction, pass into the coil of the electromagnet in such...
Page 136 - The magneto-electric machines which have been hitherto described are actuated either by a permanent magnet or by an electro-magnet deriving its power from a rheomotor placed in the circuit of its coil. In the present note I intend to show that an electro-magnet, if it possess at the commencement the slightest polarity, may become a powerful magnet by the gradually augmenting currents which itself originates.
Page 139 - ... but immediately afterwards the glow disappeared, and only about one inch of the wire could be permanently kept at a red heat. This diminution of effect was accompanied by a great increase of the resistance of the machine. The cause of the momentary strong effect was, that the machine from its acquired momentum continued its motion for a few seconds, though it required a stronger force than could be applied to maintain that motion. Each time the circuit is broken and recompleted, the same effect...
Page 135 - ... it is not even necessary to give any external impulse upon restarting the machine, the residuary magnetism of the electro-magnetic arrangements employed being found sufficient for that purpose. "The mechanical arrangement best suited for the production of these currents is that originally prepared by Dr. Werner Siemens, in 1857...