Skip to main content
Hide Articles List

11 articles on this Page

Advertising

Swansea Harbour Trust.

FOREIGN ARRIVALS A 0 MOVEMENTS…

-------Local Chartering.

Advertising

torn

I JERRY'S VOTERS HAD OBSTACLES.

Pit

Micros Photography and Armour…

Diamonds and X-RRYA-

The Mystery of the Echo

News
Cite
Share

The Mystery of the Echo fhe sconce of acoustics is, as yet, in its hfanoy, ind men nave much to learn before they <. .n solve the mystery of tfee echo or predict her fleeting moods, writes Miss G-ertrude Bacor in ^o»d Word* tolatea in general terms the explanation of erhcw simple and easy to understand. SounC, as we know, is conveyed +,0 us by vibrations of the aiif, which spread around from the source of sound Katactly as waves of —iter spread in ever widening fftngs when a pebble Is thrown into a still lake. Very frequently it happens that these wavea of IOWld, in their outward course, strike against some Surface of such a nature that they are, by it, ieflected bac\ again without being broken and Scattered. Aud when it occurs that these wave* <M returned at iuch an angle as to strike the ear of a listener, we have what we call an echo. Often More than one reflection goes to th* making up ot an echo, the sound-waves being thrown from ov* •orfaee to another in their passage to the ear-jusf M a billiard ball will rebound from cushion V oashion on its way round the table. This, roughil do the cai-,se of the phenomenon. But so endles* Me the variations of circumstances ind inTiron- WMnt, and the effects they produce so far-reaching and hard to foresee, that we are continuaUy being taken unawares. Sometimes ¡-.he echo returns at fwickly that it cannot be distinguished front th* Mnglnal sound; and yet its undetected pret- aoce is enough to affect seriously the penetration Off a coice in a church or theatre Sometimes enc found will produce several echoes in different directions, which return and return again at different time intervals, to the great distraction ot fee hearers- Again the surface of the reflecting Object has a great deal to do with the nature M the echo returned. Certain substances seem to bave a tendency to absorb the sound-waves, aai Others to eflect them more readily. Another curious property of sound-waves, exemplified in many wall- V»owia buildiBgs, is the tendency » the waves te run found a apse or galle*<% aouch as » iravo of the sea, striking aslant on a shallow bay, Will mn round the shflft. This is th# explaaatta* ■ many familiar ac-onMtic curio*iti<-s. not*My M SifSMMs Whiaj^ring ttoUocy «( St. It+ml'