Part 13 (1/2)
Less than a century ago Benja rod, in order to prevent lightning fro objects The literature of that day abounds with instances of protests made, on the part of those ere as superstitions as the people in ancient tied that it was iued that the lightning was one way in which the Creator manifested His displeasure, and exercised His power to strike the wicked
When such writers as Pliny will gravely set forth an explanation of the causes of lightning, as follows in the paragraph beloe can understand why it inculcated superstitious fears in the people of ancient tinorant of that secret, which, by close observation of the heavens, deep scholars and principalhave found out, namely, that they are the fires of the upperhtning; but those especially which are seated in the middle, that is about Jupiter, perhaps because participating in the excessive cold and moisture from the upper circle of Saturn, and the immoderate heat of Mars, that is next beneath, by this es his superfluity, and therefore it is co' Therefore, like as out of a burning piece of wood a coal flieth forth with a crack, even so from a star is spit out, as it were, and voided forth this celestial fire, carrying with it presages of future things; so that the heavens showeth divine operations, even in these parcels and portions which are rejected and cast away as superfluous”
CHAPTER XVII
POWER, AND VARIOUS OTHER ELECTRICAL MANIFESTATIONS
It would be difficult to mention any direction in huent in soave this great power into the hands of man to use, and not to curse
When the dynamo was first developed it did not appear possible that it could generate electricity, and then use that electricity in order to turn the dynamo in the opposite direction It all see should practically follow; but man had to learn this
Let us try to make the stateoing over the chapter on theof the dynaeneration of the current depends on the changing of the direction of the flow of an electric current
Look at the siradually moved toward each other, so that the north pole of one approaches the north pole of the other, there is a sensible attempt for them to push away from each other If, however, one of them is turned, so that the north pole of one is opposite the south pole of the other, they will draw together
In this we have the foundation physical action of the dynamo and the motor When power is applied to an arnetic field, the action is just the sa the north and the south pole of the two approaching nets from each other
The influence of the electrical disturbance produced by that act per of the field and armature, and extended out on the whole line hich the dynamo was connected In this way a current was established and transmitted, and with proper wires was sent in the form of circuits and distributed so as to do work
But an electric current, without suitable mechanism, is of no value It must have ht, we have explained how the arc and the incandescent la to get so from it in the way of power, means another piece of mechanism This is done by the motor, and thisthe action of the electricity
Attention is called to Figs 120 and 121 Let us assunets B, B the negatives The revolving ar positive, and the other two, D, D, negative, each of theseso connected up that they will reverse the polarities of the s 120-121_ ACTION OF MAGNETS IN A DYNAMO]
Now in the particular position of the revolving arnets of the armature have just passed the respective poles of the field nets, and the belt E is compelled to turn the armature past the pole pieces by force in the direction of the arrow F After the ar 121, the positives A try to draw back the negatives D of the aratives D, because they are of the saatives A, B continues until the arhtly passed theed; so that it will be seen, by reference to Fig 122, that D is now retreating fro forced away contrary to their natural attractive influences, and in Fig
123, when the coain approaching each other and the negatives s 122-123_ CYCLE ACTION IN DYNAMO]
In this nets are conetic pull This explains the dyna 124 that the negativethe positive and negativethe positive and negatives on the other side The positives A, therefore, attract the negatives D, and the negative B exert a pull on the positives C at the same time The result is that the armature is caused to revolve, as shown by the dart G, in a direction opposite to the dart in Fig 120
[Illustration: _Figs 124-125_ ACTION OF MAGNETS IN MOTOR]
When the pole pieces of the125, it is necessary to change the polarities of the ar 126, it will be seen that they are now indicated as C-, and D+, respectively, and have125), where the pull on one side, and the push on the other are again the saure 127 shows the cycle nearly completed
The shaft of the motor armature is now the element which turns the mechanism which is to be operated To convert electrical ireat loss The first step is to take the steae in that source which is thewater into steam The second is to use the pressure of this steaenerates the electrical impulse; and the fourth is the conversion from the dynamo into a reat probles 126-127_ POSITIONS OF MAGNETS IN MOTOR]
The great advantage of electrical power is not in utilizing it for consues, but where it is desired to trans distances Such illustrations may be found in electric railways, and where water power can be obtained as the priy, the cost is not excessive It is found, however, that even with the most improved forms of mechanisines are far y_