Electro-magnetism: History of Davenport's Invention of the Application of Electro-magnetism to Machinery... Also, Extracts from Other Public Journals...G. & C. Carvill, 1837 - 94 pages |
From inside the book
Results 1-5 of 16
Page 7
... rotating motion by repeated changes of magnetic poles , he was aware that his machine , in common with most other first inventions , admitted of , and even required , several improvements before it could be advantageously brought into ...
... rotating motion by repeated changes of magnetic poles , he was aware that his machine , in common with most other first inventions , admitted of , and even required , several improvements before it could be advantageously brought into ...
Page 15
... rotation . The iron cross bars are wound with copper wire , covered by cot- ton , and are made to form , at pleasure , a proper connexion with a circular battery , made of concentric cylinders of cop- per and zinc , which can be ...
... rotation . The iron cross bars are wound with copper wire , covered by cot- ton , and are made to form , at pleasure , a proper connexion with a circular battery , made of concentric cylinders of cop- per and zinc , which can be ...
Page 16
... Rotating Machine , composed entirely of Electro - Magnets , both in Fixed and Revolving Members . A machine of this construction has been this day , March 29 , 1837 , exhibited to me by Mr. Thomas Davenport , himself , who came from New ...
... Rotating Machine , composed entirely of Electro - Magnets , both in Fixed and Revolving Members . A machine of this construction has been this day , March 29 , 1837 , exhibited to me by Mr. Thomas Davenport , himself , who came from New ...
Page 49
... the pole of the earth's rotation , nor does it extend to low latitudes . It generally appears in the form of a lumi , nous arch , stretching more or less from east to west , but never from north to south ; across the arch the 49.
... the pole of the earth's rotation , nor does it extend to low latitudes . It generally appears in the form of a lumi , nous arch , stretching more or less from east to west , but never from north to south ; across the arch the 49.
Page 56
... rotation . In conse- quence of their attraction and repulsion , a needle freely sus- pended , whether it be magnetic or not , only remains in equi- librio when in the magnetic meridan , that is , in the plane which passes through the ...
... rotation . In conse- quence of their attraction and repulsion , a needle freely sus- pended , whether it be magnetic or not , only remains in equi- librio when in the magnetic meridan , that is , in the plane which passes through the ...
Common terms and phrases
acid acidulated water agent apparatus application attraction and repulsion bodies chemical action chemical decomposition circle common electricity conductors consequently Cook copper slip copper wire current of electricity cylinder Davenport deflected direction discovery distance earth effects elec electric currents electric fluid electro-dynamics electro-magnetic energy engine equilibrium exhibited experiments Faraday feeble galvanic battery galvanic magnet galvanometer heat helix inches increase indefinitely induction insulated intensity invention iron cross kind of electricity machinery magnetic needle magnetic pole magnetised material matter mechanical ment metallic moving mysterious negative electricity netic neutral north pole observed opposite particles patent phenomena plate polarity positive electricity pounds Princeton College principle produced properties quantity of electricity repel revolutions per minute revolve right angles rotary motion rotation soft iron solar light south pole steam steel substances subtile surface suspended terrestrial magnetism theory Thomas Davenport tion tricity voltaic electricity zinc
Popular passages
Page 49 - Suppose that the two extremities of a cloud highly charged with electricity hang down towards the earth ; they will repel the electricity from the earth's surface, if it be of the same kind with their own, and will attract the other kind ; and, if a discharge should suddenly take place at one end of the cloud, the equilibrium will instantly be restored by a flash at that point of the earth which is under the other. Though...
Page 88 - Hence arises still further confirmation, if any were required, of the identity of common and voltaic electricity, and that the differences of intensity and quantity are quite sufficient to account for what were supposed to be their distinctive qualities.
Page 85 - ... to complete the circuit, these currents could not exist. Since the motion, not only of metals but even of fluids, when under the influence of powerful magnets, evolves electricity, it is probable that the gulf stream may exert a sensible influence upon the forms of the lines of magnetic variation, in consequence of electric currents moving across it, by the electro-magnetic induction of the earth.
Page 56 - There are places where the magnetic meridian coincides with the terrestrial meridian ; in these a magnetic needle freely suspended points to the true north; but if it be carried successively to different places on the earth's surface, its direction will deviate sometimes to the east and sometimes to the west of north. Lines drawn on the globe, through all the places where the needle points due north and south, are called lines of no variation, and they are extremely complicated.
Page 16 - But it is an important fact, discovered by experience, that the latter is soon impaired in its power by the influence of the revolving galvanic magnet, which is easily made to surpass it in energy, and thus, as it were, to overpower it. It is obvious, therefore, that the fixed magnet, as well as the revolving, ought to be magnetized by galvanism, and then there is every reason to believe that the relative equality of the two, and of course their relative energy, may be permanently supported, and...
Page 17 - The entire apparatus is therefore constructed of soft unmagnetic iron, which being properly wound with insulated copper wire, is magnetized in an instant, by the power of a very small battery. The machine is indeed the identical one used before, except that the exterior circle of permanent magnets is removed and in its place is arranged a circle of soft iron, divided into two portions to form the poles. These semicircles are made of hoop iron, one inch in width, and one eighth of an inch in thickness.
Page 80 - The electro-magnetic effect of the elective current induced in a conductor by a magnetic pole, in consequence of their relative motion, is such as tends continually to diminish that relative motion ; that is, to bring the moving bodies into a state of relative rest : so that, if the one be made to revolve by an extraneous force, the other will tend to revolve with it, in the same direction, and with the same velocity.
Page 48 - ... that they owe their existence, or at least their form, to that fluid. It is very probable that when two currents of dry air are moving different ways, the friction of the two surfaces may evolve electricity. Should these currents be of different temperatures, a portion of the...
Page 48 - When two clouds, charged with opposite kinds, approach -within a certain distance, the thickness of the coating of electricity increases on the two sides of the clouds that are nearest to one another ; and when the accumulation becomes so great as to overcome the coercive pressure of the atmosphere, a discharge takes place, which occasions a flash of lightning. The actual quantity of electricity in any...
Page 21 - Thomas Davenport. In the words of the patent, taken out, this invention " consists in applying magnetic and electro-magnetic power as a moving principle for machinery, in the manner described, or in any other substantially the same in principle.