This shows that for every tone an air column of a certain size most powerfully reinforces that tone.
"Resonance in Singing and Speaking"
Thomas Fillebrown
When a child is baptised, the spiritual energy given to the water by the Word and the Sign reinforces the spiritual life in the child, and then the Word of Power is again spoken, this time over the child, and the Sign is traced on his forehead, and in his subtle bodies the vibrations are felt, and the summons to guard the life thus sanctified goes forth through the invisible world; for this Sign is at once purifying and protective-purifying by the life that is poured forth through it, protective by the vibrations it sets up in the subtle bodies.
"Esoteric Christianity, or The Lesser Mysteries"
Annie Besant
For in such a place there is not only the magnetisation produced by a single saint, or by the visit of some great Being of the invisible world; each person, who visits the spot with a heart full of reverence and devotion, and is attuned to its vibrations, reinforces those vibrations with his own life, and leaves the spot better than it was when he came to it.
"Esoteric Christianity, or The Lesser Mysteries"
Annie Besant