Evening star. [volume] (Washington, D.C.) 1854-1972, 1930-11-23

Pa river. Shoals. rocks and other distractions
show ON the map unless they are too deep to
interfere with navigation
Sand barriers at the mouth Of the Indian
River inlet formed obstruction. These were
battered out by stoEmAp producing new eondi-
tons. Sounding would have been a long and
difficult task. An aerial survey was made and
the taking Of . small number of photographs
revealed the new conditions.
One Of the most remarkable Of riveT-channel
surveys was made By air for q city which was
suffering from water pollution. Some indus
trial plant was pouring refuse into the river.
bat 1t seemed impossible to locate the offender.
The air mapmakers new above the river.
taking their photographs. When the map was
put together it revealed the source of the poll
luton. From o large Industrial plant located
On the river bank q black blur entered the river,
widened and then gradually disappeared.
This is only one instance that shows the
versatility Of the work Of the aerial surveyor.
He is more than q mapmaker; he Is an inves-
tgatOr and sometimes Q detective. For his
maps are more than lines and marks; they
actually portray existing conditions and they
are correct to minute details
A large oil company intended to buy Q tract
Of land. It had no suitable map; there were
reasons Why the company could not send men
TO go over all the territory involved. An aerial
surveyor took the JOB and covered the ground
IN very short time. His map showed his em-
ployers everything they needed to know.
1arge-scale map. made above forests or
agricultural land, does more than show the
mere outline Of the terrain. It enables the man
who studies the map to estimate accurately
just how much timber there Is in wooded tracts
or to discover the exact condition of crops and
grain.
An aerial surveyor was called upon TO map
the grounds around q hotel IN Canada. The
map was on a large scale, and when the hotel
manager examined it he was surprised to ind
the trace Of path leading from the hotel to
q nearby river.
The manager maintained that the path did
not exist; the mapmaker answered the chal-
lenge and upheld the accuracy Of the camera.
They searched for the path and found it, al.
though It was very faint. Following it to the
river bank, among q cluster Of trees they dis
covered cache Of goods stolen from the hotel
The thieves in carrying the goods to this spot.
had unconsciously made a path and the air
map revealed the evidence that led to their
capture.
"A lawsuit in Havana, Cuba, depended upon
obtaining immediate information regarding
existing conditions in railroad yard. Tho
railroad company refused admission to ito
ground. The aerial surveyor was called in He
made brief flight: his camcraman snapped
the whole scene and the evidence was IN the
bag.
Philadelphia recently made use of an aerial
survey in connection with the study Of the
proper route for the northeast extension from
Its Broad street subway. There were plenty Of
ordinary maps available; they showed suitable
routes, but they gave very little information re-
garding property developments along the routes
that were under consideration
Victor Dalin, an aerial surveyor, covered the
territory Of 26 miles in approximately 70 hours,
and the result was . large-scale map that
showed houses, vacant lots and conditions Of
buildings as they actually existed. In place Of
obsolete and incomplete maps, the transit d.
rector had an up-to-date chart that was alive
with vital Information.