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A NEW DUST COUNTER
D U S T , which, like the mosquito,
has long been regarded
merely as an annoyance, has
turned out to be an active
menace to health, if not to
life itself. With every breath, we draw
into our lungs countless dust particles,
which are just as useful and handy in
our breathing mechanism as they would
be in the mechanism of a watch. The
war against dust which is being waged
by public health officials, has resulted in
the invention of a new means for counting
the number of dust particles in a
given quantity of air. This war is the
tight for "The Straight Red Line."
What is this straight red line? On a
chart on which conditions of ventilation
are plotted graphically, the straight line
along the bottom represents ideal conditions
of ventilation—a rating of one
hundred per cent perfect. This condition
has been attained just once, on the
deck of a boat in the middle of Lake
Michigan on a mid-summer day. Here
the conditions were plotted on a chart
as a straight red line along the bottom.
In our schools, factories, churches, and
theaters, however, the red line is a
crooked affair, as yet, and one of the
pieces of artillery which will help us
pound our way to the straight red line
here is the new dust-counter which has
been invented by Dr. E. V. Hill, chief
of the Ventilation Bureau of the city of
Chicago health department.
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