In audio signal processing and acoustics, an echo (plural echoes) is a reflection of sound, arriving at the listener some time after the direct sound. Typical examples are the echo produced by the bottom of a well, by a building, or by the walls of an enclosed room and an empty room. A true echo is a single reflection of the sound source. The time delay is the extra distance divided by the speed of sound. Wikipedia, Echo
Russell
"The principle of projection is the same that man uses in projecting the concept of his idea into the moving form of the idea. It is the dual radar principle of Nature. Reduced to its ultimate simplicity, Nature is a series of echoes." [Atomic Suicide, page 253]
"A mirror placed parallel in plane with the direction of the shaft of gravity, would naturally, show a reverse direction of spinning. But radar, or echo mirrors of Nature are not placed that way. They are placed at angles of 90 degrees from gravity shaft. See Fig. 81." [Atomic Suicide, page 296]
"God's end of the cosmic
Bridge where motion begins
Its projection into space
To simulate mind-idea.
Matter begins by division of stillness in the inert gases and its projection by two-way motion into pairs of octave wave tones, which we call elements. The principle of projection is the same that man uses in projecting the concept of his idea into the moving form of the idea. It is the dual radar principle of Nature. Reduced to its ultimate simplicity, Nature is a series of echoes." [Atomic Suicide - Fig 62]
Hughes
General remarks on the method of harmonies developing on all kinds of instruments, including the human voice
—Much paradox, but yet the scheme will admit of clear demonstration
—A musical note compared to a machine, the motive power not of our creation
—The imperfection of keyed instruments, from some notes acting two parts, attuned to the ideal of harmony within us
—Macfarren quoted on the echoing power of a cathedral attuning the Amen
—Why music as an art precedes painting
—Philosophers and mathematicians have only studied music to a certain point
—Every key-note a nucleus, including the past, the present, and the future; no finality in any ultimate
—The late Sir John Herschel's views on the musical gamut alluded to
—The imperfection of keyed instruments adapts them to our present powers
—The laws will be seen to develope the twelve major and the twelve minor keys in unbroken sequence and in harmonious ratio; to gain them in geometric order [as] keyed instrument should be circular, the seven octaves interlacing in tones a lower and a higher series, . 15 [Harmonies of Tones and Colours, Table of Contents1 - Harmonies]
study of the natural sciences, as we progress, we find that "hills peep o'er hills, and alps o'er alps arise." As regards keyed instruments, it appears that the effect of those notes which act two parts, such as C# and D?, is rectified in some way so as to be perfectly attuned to the ideal of harmony within us. Again, the "Amen" sung by the choir in a cathedral may not be in accurate tune, but if nearly the correct intonation is sounded, after traveling along the aisles, the chords always return to the ear in perfect harmony, because the natural laws of music, assisted by the echoing power of the building, have attuned them to the perfect harmonical triad. If the "Amen" be too much out of tune, these laws decline to interfere, and there is no such helpful resonance.* [Harmonies of Tones and Colours, The Method of Development or Creation of Harmonies2, page 16]
The primitive laws of any science should be capable of succinct statement, but in combination with others they become more complex and delicate, and error is proved if in the developments they do not echo each other. If, therefore, musical harmonies are correctly gained, the same laws will develope harmonies of colour, and will agree with the colours of the rainbow, the circle of which is divided by the horizon. All who are interested in the laws which regulate these two sciences will doubtless know the interesting lectures delivered by W. F. Barrett (Professor of Experimental Physics in the Royal College of Science, Dublin), and the article written by him and published in the Quarterly Journal of Science, January, 1870, entitled "Light and Sound; an examination of their reputed analogy, showing the oneness of colour and music as a physical basis." I will quote shortly from the latter for the benefit of those who may not have met with it. "The question arises, Has all this æsthetic oneness of colour and music any physical foundation, over and above the general analogy we have so far traced between light and sound? We believe the following considerations will show, not only that it has some foundation, but that the analogy is far more wonderful than has hitherto been [Harmonies of Tones and Colours, On Colours as Developed by the same Laws as Musical Harmonies1, page 18]
See Also
Absorption
Law of Cycles
Law of Force
Light Mirror
Neutral Center
Principle of Regeneration
Radar
Radiation
Reflection
regenerate
Regeneration
Reincarnation
Repeat
Repetition
reproduce
Velocity of Sound