Keely's third system embraced AERIAL and SUBMARINE navigation.
The secret of production of the "vibratory lift" is embraced in his statement elsewhere "Any metallic mass can be so impregnated with certain vibrations as to give it the mental attributes of attraction and repulsion." He simply impregnated the particular metallic mass with vibrations which caused it to assume self-repulsion to the terrestrial or earth mass chord, and this repulsion thrust it away, out to us, upwards.
In the spring of 1890 he succeeded in raising the metal weight composing his air-ship model, by means of a force still unknown to science. One of his friends stated "When he has gained as perfect control of it as we now have over steam, air-ships weighing thousands of tons can easily traverse the highways of the air."
"He has gained control of the mysterious polar current to that extent that he has been able to exhibit on the thirds or molecular graduation of the propellor of his air-ship, 120 revolutions per minute, and on the sixths or atomic graduation, 360 revolutions per minute. He still has the etheric field to conquer."
Keely says "By exciting the metallic mass composing a navigator of any given weight, it may be suspended and propelled. The vibratory neutral negative attraction evolved will bring it into perfect commercial control by keeping it in sympathy with the earth's polar stream." This is why he sought to find the sympathetic connection between luminous ether, or inflowing celestial streams, and the radiating or terrestrial streams, which, by their interaction "solar tensions against terrestrial condensations" cause the polar current and its kindred phenomena.
While he used "sympathetic negative attraction" for running machinery, he sought to use for aerial navigation, another force, a "negation" of "sympathetic negative attraction" or the same force that regulates the recession of the planets from each other. This is probably simply polar propulsion, although he terms this elsewhere as gravity.
"The power of the terrestrial propulsive and celestial attractive is to lift and of the celestial propulsive and terrestrial attractive is to descend. Certain polar or antipolar vibrations can intensify either of these qualities so as to cause either of them to predominate. Intensifying the celestial will cause a metallic mass to rise with a speed proportionate to the concentration of the dominant bearing on the negative thirds of its mass chords, thereby inducing high neutral radiation together with celestial attraction."
"An air-ship of any number of tons weight can, when my system is completed, float off into space with a motion as light as thistledown, or with a velocity out rivaling the cyclone. With the force of corpuscular bombardment its movements can be as varied as is necessary for commercial use at any desired elevation and at any speed."