strial districts, such as that of Saint
Etienne, and hopes that some mine doctor will throw additional light
on the subject. In the meanwhile, it may be suggested that the
ventilating effect of the numerous chimneys in iron making and other
industrial centers has its due share in constantly driving off the
vitiated air and replacing it by fresh quantities of pure air. At any
rate, when pestilence was raging in the high and pleasant quarter of
Clifton, its inhabitants migrated to the low-lying and not overclean
parish of St. Philips, Bristol, where the air is black from the smoke
of numerous chimneys, but where also the mortality compared very
favorably with that in the fashionable quarter.

A TWO-SPEED movable sidewalk, of the Blot, Guyenet and De Mocomble
type, is to be used for conveying visitors at the Paris Exposition,
says Engineering News. It differs from those of Chicago and Berlin in
the reduction of the weight of the moving platform by spacing the
driving wheels 127.5 feet apart and using electricity as a motive
power. The driving wheels are mounted in the bed of the track and
impart motion to a central rail on the under side of the platform.
Bearing wheels, spaced about 20 feet apart under this rail, also carry
the platform, and the central rail supports one-half the total weight
of the platform; small side wheels carry the other half on side
tracks. This arrangement enables the platform, which is divided into
sections and hinged, to pass around quite sharp curves. The high speed
platform, 4 feet 3 inches wide, is supposed to move at the rate of
61/2 miles per hour on a 351/2-inch gage track; the slow platform is
311/2 inches wide, moves at half speed and runs on a 17-3/4-inch gage
track. The whole structure will be elevated on girders carried by cast
iron columns, with stations about 656 feet apart. The high speed
platform weighs 146 pounds per lineal foot; and with passengers,
nearly 400 pounds per foot. The slow speed platform weighs about half
this. The track will be about 21/2 miles long; the initial motive
power is figured at 472 H.P. and the carrying capacity at 38,880 per
hour.

THE "SCHLAMM," or mud, thrown down from the water of coal washing
has hitherto been regarded as worthless, says The Engineering and
Mining Journal, except that sometimes a portion of the coal particles
it contained have been separated and made of value by a washing
process; but Bergassessor Haarmann, of Friedrichsthal, has in