A guide to the scientific knowledge of things familiar / by the Rev. Dr. Brewer.
- E. Cobham Brewer
- Date:
- [1853]
Licence: Public Domain Mark
Credit: A guide to the scientific knowledge of things familiar / by the Rev. Dr. Brewer. Source: Wellcome Collection.
440/496 page 434
![cannot pass through the cavern or grotto, are driven back again from their sides. Q. Wluj are halls, winding passages, ruins,, and cathedral aisles, FAMOUs/or echoes? A. Because the sound-waves cannot' flow freely forward in them: but strike; against the opposing walls and are beateni ^ hack. I Q. Why are mountains, and ice-bergs famouss for ECHOES ? A. Because they present an insur- « mountable harrier to the sound-waves,, and throio them hach again. ' Q. Why do not the walls of an ordinary] i BOOM or small church produce jjercejdihle-echo ? ( A. Because sound travels with such velocity, that the echo is hlended with the ^ original sound; and the two produce but || one impression on the air. n Sound travels 13 miles in a minute; and no perfect echo ij heard, unless the surface (against which the sound strikes) is b.- j feet from the place, whence the sound ongmally proceeded. Q. Why do very labge buildings (as cathe^ drals), often keveebebate the voice of the speaker: Si A. Because the walls are so far ojj lit from the speaker, that the echo does no. j get hach in time to-blend with the origma. \'](https://iiif.wellcomecollection.org/image/b21495464_0440.jp2/full/800%2C/0/default.jpg)
