The Appeal. [volume] (Saint Paul, Minn. ;) 1889-19??, 1912-11-09

already about six hundred feet up, when Lieu
tenant Burlez overlook him, passing at greater
speed something like a hundred feet above.
Lieutenant Burlezs machine created SO 1t is said,
downward moving hole in the air." and this
struck Lieutenant Briefs monoplane in such a
manner as to destroy it's equilibrium. Lieutenant
Brez and his machine dashed to the earth,
the aviator having both legs broken and being
otherwise seriously but not fatally injured. III
this case the innocent cause of the accident was
the movement of the aeroplane passing above
at height of hundred feet while Mile Du-
tr1eus drop was probably brought about by the
maneuvering of the two monoplanes beneath
her. These accidents have brought us face to
face with problems in the art of mechanical
fght-they show us that we have much to learn
about the air in which are seeking to vie
with the bird
The man in the street has mistaken notion
of what these air holes really are; he imagines
that they are areas of partial vacuum which fail
to give the flying machine proper support. The
hazard they present is reasonably pictured all
the greater because there is visible sign of
their presence-the aircraft just suddenly starts
to drop and may fall several hundred feet before
the movement be corrected, If corrected at
all. II successful the incest Judgment is required
on the part OF the aviator lest he suddenly bring
pressure to bear upon his planes in excess of
their reserve Of strength. Collapse of this sort
has happened with dire results upon number of
occasions. But, Notwithstanding these physical
evidences OF something wrong, STILL In the strict
or sense OF the word, the term air hole Is a mis-
homer. and cavity such does not really exist.
Did you ever watch the surface agitation of a
boiling pot? Well that is substantially dupli-
cation of just what is going on in the air about
us. The earth acts like great reflector of the
suns heat and starts the air boiling below here
where we are and sends it upward in great col
umns of rising atmosphere like the movement of
the boiling water in the pot. This is what the
meteorologist calls "convectional disturbances"
of the atmosphere and he tells us that this state
of things would not annoy the aviator if the ven
turesome airman would only keep aloft at
height of from four to five miles-a matter OF
from $1,000 to $4,000 feet in round numbers!
Georges Legagneux has recently reached the
amazing height of 1876 feet
We are all familiar with the old saying. What
goes up must come down.. In the agitated belt
of air the upward rising column OF warm air is
replaced by descending column Of cooler air.
The downward moving column Is what really con-
stitutes the so-called 'holes" Of the aeronaut's
parlance. The layman scarcely appreciates the
conditions that are bringing about this convec-
ton or boiling motion. When the sun strikes the
earth the air is heated and rises; In the shadow
OF a cloud the air is cooler and descending. This
see-sawing is Of greater or lesser magnitude, de-
pending upon the directness of the suns rays
and the temperature of, the air when shaded.
The evenness of the aviators fight or the uni
formity of his line of advance-whichever you
choose to call it's controlled by the constancy
of the pressure which the air exerts on the
under or lifting side of the planes as his machine
is driven forward by Its motor. The net result
Is sustaining or lifting moment, as the engineer
expresses It.. Il the approaching air. instead OF