Richmond times-dispatch. [volume] (Richmond, Va.) 1914-current, 1921-03-27

fiT"cIIonal wireless and echo direction"
II vas difficult matter to locate the posi-.
ton Of a distant big gun because an cx-
plosion produces sudden impulse propa.
gaied equally in all directions In locating
guns The physicists used three wireless
telephone receivers in known positions,
and we're able 10 locate Approximately the
direction OF the explosion IA modification
OF the same apparatus was used in locating
ships at sea
Scientific investigators have cxpnrim 1t
ed with sounh-wavcs OF 5000 TO 10 coo peri.
DDS per second. which IS far below the short
est wavepcriods audible by man When such
a beam Of sound of high frequency. com
parable to n scarchiEht falls upon an oh.
staclc, IL is reflected or echoed, and tho
echo IS detected by "A hydrophonc An in
stIumcnt based on this idea has proved
somewhat us"rul In detecting rocks and
ships, but not in locating icebcrgs, which
have elastic properties similar 10 those of
water.
The ears OF man arc very uncertain and
unreliable in detecting the direction Of
sounds. even when rhcsc are loud enough
To be heard. BY increasing the distance
apparatus a great increase Of accuracy in
locating the direction Gf sound is obtained.
Another apparatus has been invented 10
rive the blind man knowledge OF his SUR
roundincs through his ears as The bat re-
ccivcs its Impressions.
On the other hand. the bat Is able 10
locate the position OF objects very &C.
cnrateiy, even though its funny ears arc
very close together because tho sounds
emitted ana reflected to its ears are OF
very short wavc-lcngth.
Bats possess powers of flight superior
10 that OF many birds This may be in
ferred from the fact that q red bat has
been known 10 catch flies IN the air while
burdencd with young that together
weighed more than she did.
Most California bats catch and devour
prey on the wing. They bite off and re-
ject the hard parts of insects. In the
Autumn bats become very fat ready for
migration or Information Even the bats
on the wing all the year rely on this
stored Fat to balance Il scarcity of insects
BATS are as valuable to men as are any
OF the insec,ivorous birds. They are re-
lcntless and untrng hunters and destroy
crs of mosquitoes, and this makes ii very
desirable 10 encourage them. San Antonio
Texas, and other towns have constructed
"bat roosts" in order to encourage tho lit
Tie dUlHldtS 10 DIpeH anu destroy mos
quitoes. The bats attack nearly all tho
nocturnal insects, especially the disease
carriers.
They are very difficult 10 shoot because
OF their swift. crratic flight. IL has heen
asserted by some naturalists that they
have the power TO dodge shot through
their phenomenal sense.
They are powerful swimmers and have
the habit of going into the water in
search OF insects.
In connection with The power Of bats to
avoid obstacles in tho dark It. Is interest
ing to recall the explanations that havo
been advocated Of the blind mans power
of avoiding collisions. Persons who have
been long blind often show Il remarkable
ability to avoid collisions with walls. posts
and other lifeless objects. Professor c. II.
Fraser. Of Nova Scotia. has shown that
this is because person in moving drives
4 slight wave of air before him. When this
strikes solid object it is thrown back,
and some blind men are clever enough to
perceive the proximity Of solid objects In
this. II has been argued not unreasonably
that the bats power to avoid obstacles was
due to similar conditions, but investiga-
tion seems to prove that the animals
power is too delicate and unerring to be
explained in this way.