These venerable trees have now been fenced in, but, with certain
restrictions, they will continue to be accessible to all who wish to
inspect them. In future no encampments will be permitted within the
enclosure, except in the part marked out for that purpose by the keeper,
nor may any cooking or camp fires be lighted near the trees.
* * * * *
ON THE MECHANICAL PRODUCTION OF ELECTRIC CURRENTS.
The object of these articles is to lay down in the simplest and most
intelligible way the principles which are concerned in the mechanical
production of electric currents. Every one knows now that electric
lights are produced from powerful currents of electricity generated in
a machine containing magnets and coils of wire, and driven by a steam
engine, or gas engine, or water-wheel. But of the thousands who have
heard that a steam engine can thus provide us with electric currents,
how many are there who comprehend the action of the generator or
dynamo-electric machine? How many, of engineers even, can explain where
the electricity comes from, or how the mechanical power is converted
into electrical energy, or what the magnetism of the iron magnets has
to do with it all? Take any one of the dynamo-electric machines of
the present date--the Siemens, the Gramme, the Brush, or the Edison
machine--of each of these there exist descriptions excellent in their
way, and sufficient for men already versed in the technicalities of
electric science.
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