on the
beach and out on the water, where they seemed to be passing to and fro
between the land and a vessel that was dimly visible in the little
harbor. He could also hear loud rough voices, and, as Cal had said, some
of them were swearing.

[TO BE CONTINUED.]

THE BUILDING OF MODERN WONDERS.

AN ELECTRIC TROLLEY-CAR.

BY HERBERT LAWS WEBB.

One day, not very long ago, when electric cars were something of a
novelty, a city official was talking about them to one of the electrical
engineers in charge of a certain electric railway.

"It seems to me," said he, "that those trolley-poles on top of the cars
ought to be very much stronger than they are."

"Why so?" asked the electrical man. "We very seldom have any accident
with them. They almost never break."

"Don't they!" queried the other, with some astonishment. "Well, they
don't look to me half strong enough to push those heavy cars along."

I suppose very few readers of the ROUND TABLE have such very foggy ideas
about electric cars as that man had. But still it is something of a
mystery to many people how the slender wire stretched along the street
takes the place of the hundreds of tugging horses or of the rattling,
whirring cable that glides ceaselessly through the long iron trough
under the pavement.

Many years ago one of those famous scientific men who were always making
experiments to discover new things about electricity, so as to enable
practical men in these days to invent machines to do useful work,
discovered that when he moved a wire about in front of a magnet an
electric current appeared in the wire. This was a great discovery,
because it brought to light the wonderful sympathy between magnetism and
electricity. It made no difference whether the wire or the magnet were
moved; as long as they were close enough together any movement of either
caused a current to appear in the wire.

Then another famous discoverer found that by winding a wire round a bar
of iron and sending a current of electricity through the wire he turned
the bar of iron into a magnet. As long as the current was passing
through the wire the iron bar acted just like a permanent steel magnet;
it would attract pieces of iron and hold up nails, but the moment the
current was stopped the bar lost its magnetism, the nails or pieces of
iron dropped off, and it became just an ordinary bar of iron again. This
invention is called the electro-magnet, and the electro-magnet is use