water forming greater New York are perfectly united by numerous
bridges, tunnels, and electric ferries, while the city's great
natural advantages have been enhanced and beautified by every
ingenious device. No main avenue in the newer sections is less
than two hundred feet wide, containing shade and fruit trees, a
bridle-path, broad sidewalks, and open spaces for carriages and
bicycles. Several fine diagonal streets and breathing-squares
have also been provided in the older sections, and the existing
parks have been supplemented by intermediate ones, all being
connected by parkways to form continuous chains.

"The hollow masts of our ships--to glance at another phase en
passant--carry windmills instead of sails, through which the wind
performs the work, of storing a great part of the energy required
to run them at sea, while they are discharging or loading cargo
in port; and it can, of course, work to better advantage while
they are stationary than when they are running before it. These
turbines are made entirely of light metal, and fold when not in
use, so that only the frames are visible. Sometimes these also
fold and are housed, or wholly disappear within the mast.
Steam-boilers are also placed at the foci of huge concave
mirrors, often a hundred feet in diameter, the required heat
being supplied by the sun, without smoke, instead of by bulky and
dirty coal. This discovery gave commercial value to Sahara and
other tropical deserts, which are now desirable for mill-sites
and for generating power, on account of the directness with which
they receive the sun's rays and their freedom from clouds. Mile
after mile Africa has been won for the uses of civilization, till
great stretches that were considered impassible are as productive
as gardens. Our condensers, which compress, cool, and rarefy