United States or Gibraltar ? Vote for the TOP Country of the Week !
It is evident that when we use permanent magnets or springs as directing forces in measuring instruments, we cannot count upon an absolute constancy in the indications, as the magnetism of the magnetized pieces, or the tension of the springs, modifies in time. The apparatus require to be regulated from time to time, and hence the idea of substituting electro-magnets for permanent ones.
The small weight of the mirror and magnets which form the moving part of this instrument, and the range to which the minute motions of the mirror can be magnified on the screen by the reflected beam of light, which acts as a long impalpable hand or pointer, render the mirror galvanometer marvellously sensitive to the current, especially when compared with other forms of receiving instruments.
When there is no current on the instrument, the spot of light remains stationary at the zero position on the screen; but the instant a current traverses the long wire of the coil, the suspended magnets twist themselves horizontally out of their former position, the mirror is of course inclined with them, and the beam of light is deflected along the screen to one side or the other, according to the nature of the current.
Even if the motive power was derived from a coiled spring, or compressed air, or electricity, in the box, how was it possible to make it act without the resistance offered by the air? Magnetism was equally out of the question, since no conceivable arrangement of magnets could have brought about the movements I had seen.
His brother and his brother's daughter did what he and Mary had failed to do. They were the magnets. Youth and joy and laughter drew to them. The house was lively with young life. Ever, day and night, the motor cars honked up and down the gravelled drives.
"What's all this stuff on the table?" he asked, indicating the magnets, rolls, and clockwork. Kennedy did not have time to reply, for the telephone bell was tinkling insistently. "I've got Chicago on the wire," Craig informed us, placing his hand over the transmitter as he waited for long-distance to make the final connection.
Tell him we're coming up, don't let him grab us with his magnets! This is putting you in a devil of a hole, old man. I'm sorry! but we've got to see it through now. "You can never set this ship down, Spud; that patrol would be on our backs in half a second. And they'd knock me out with one shot the minute I stepped outside."
This device consists of a large coil of very fine wire, in the center of which, in a small air-chamber, is a tiny mirror. Mounted on the back of the mirror are very small magnets. The mirror is suspended by a fiber of the finest silk.
I believe this place is a greater loss to him than to my mother. What are your plans?" "Rotifer, as before." "Chacun a son gout," said Bobus, shrugging his shoulders. "I should have thought you would respect curing more than killing." "If there were not a whole bag of stones about your neck." "Magnets," said Jock. "That's just it. All the heavier."
The magnets were made compound, laminated; a large number of thin horseshoe magnets were laid together, with opposite poles touching. These were all comparatively small machines what we now, with some reason, regard as having been toys whose present results were rather long in coming. Then came Siemens, of Berlin, in 1857.
Word Of The Day