noun: a level of quality or achievement, especially one that people generally consider normal or acceptable

Keely
He has again reduced in size the instrument producing the force. From 1882 to 1884 the "Generator" was six feet long and corresponding wide and high, but failing to make the arrangement automatic upon which its mechanical usefulness depended, Keely found a new standard for research in an experiment often made by himself, but never before successful, which resulted in invention in 1885 of the "Liberator" not so large as a lady's small round worktable. He made astonishing progress with this beautiful piece of vibratory mechanism, so as to combine the production of the power, operation of the cannon, his engine and his disintegrator in a machine no larger than a dinner plate and only three or four inches in thickness. This was completed in 1886, up to which time his experiments were upon the principle of sympathetic vibration, for liberating a vapory or etheric product. His later experiments were another modification of vibratory sympathy, and the size of the instrument used now, 1888, for the same purposes is no larger than an old fashioned silver watch. A pressure of 30,000 lbs. to the square inch in raising of the lever, and all other operations, without one ounce of pressure in any part of the apparatus, are effected by the ether. The force is transmitted along a wire of platinum and silver. Keely has named this new modification "Negative Attraction." The two forms of force with which he has experimented and the attendant phenomena, are exactly antithetical. It is by changing the vibrations of the cosmic ether that Keely releases this energy. Dr. Dupuy, of New York, experimented along these lines for many years, but without success to the degree Keely had. [underline added] [Snell Manuscript - The Book, page 3]