Electrical Engineer, Том 12

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Electrical Engineer., 1891

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Сторінка 68 - And if any one rightly compare them he will find the judgment of antiquity to be correct. For the benefits derived from inventions may extend to mankind in general, but civil benefits to particular spots alone ; the latter, moreover, last but for a time, the former for ever.
Сторінка 205 - If the head of Lee's army is at Martinsburg and the tail of it on the plank road between Fredericksburg and Chancellorsville, the animal must be very slim somewhere. Could you not break him ? " The Confederates under Ewell entered Pennsylvania June 22.
Сторінка 39 - ... protected from currents of air, it wriggles around constantly. Nevertheless, it is in this form excessively persistent, and when the terminals are approached to, say, one-third of the striking distance, it can be blown out only with difficulty. This exceptional persistency, when short, is largely due to the arc being excessively thin; presenting, therefore, a very small surface to the blast. Its great sensitiveness, when very long, is probably due to the motion of the particles of dust suspended...
Сторінка 276 - Of course, general precautions and preventive measures should be taken before any troubles occur, if possible, rather than to wait until a difficulty has arisen. For example, one should see that the machine is not overloaded or running at too high voltage, and should make sure that the oil -cups are not empty.
Сторінка 316 - When current for light and power is taken from primary or secondary batteries, the same general regulations must be observed as apply to similar apparatus fed from dynamo generators developing the same difference of potential.
Сторінка 276 - Fig. 59. simply moving the rocker-arm. If only slightly out of position, heating alone may result, without disarrangement being bad enough to show sparking. If the brushes are not exactly opposite in a bipolar, 90° apart in a four-pole machine, and so on, they should be made so, the proper points of contact being determined by counting the commutator-bars or by careful measurement. The usual position for brushes is opposite the spaces between the pole pieces, but in some machines they must be set...
Сторінка 394 - This fault is due either to a defect in the original construction, or to wear in the bearings, either of which is difficult to correct; but in cases of necessity the armature can be centered exactly in the field by moving the bearings, which may be done by carefully filing the holes through which the screws pass that hold the bearings in place; or the pole piece may be filed away where it is too near the armature.
Сторінка 68 - Less gas was occluded during the progress of this experiment than in the case of platinum. The silver behaved the same as gold, the metal deposited freely, and the vacuum was easily kept at a dark space of 6 mm. by the very occasional admis1891.] Chemistry of the Plante Cell.
Сторінка 48 - In all cases, then, when we excite luminosity in exhausted tubes by means of such a coil, the effect is due to the rapidly alternating electrostatic potential; and, furthermore, it must be attributed to the harmonic alternation produced directly by the machine, and not to any superimposed vibration which might be thought to exist. Such superimposed vibrations are impossible when we work with an alternate current machine. If a spring be gradually tightened and released, it does not perform independent...
Сторінка 316 - Must be capable of being disconnected at the power plant, or of being divided into sections, so that, in case of fire on the railway route, the current may be shut off from the particular section and not interfere with the work of the firemen. This rule also applies to feeders.

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