1. As a _participial_ noun, or participle in Nipth נבוב Neboob, hollow, made hollow, &c. 2. It is applied spiritually, hollow, empty, vain. 3. To the sight, or pupil of the eye; that part of the eye which appears hollow, and admits the light. See Parkhurst's Hebrew Lexicon. Had the learned translators of our bible possessed a knowledge of the theory of concentric spheres, it is probable they would have given the English reader the most correct meaning of the words, תהו ובהו "_without form and hollow_," or "_shapeless and hollow_." CHAPTER VIII. _General observations on the Theory of Concentric Spheres, with a few suggestions to the Congress of the United States, to authorize and fit out an Expedition for the discovery of the Interior Regions; or, at least, to explore the northern parts of the continent of America._ Of the many various and conflicting theories which have been advanced, relative to the form, structure, and motion of the earth, the theory of Concentric Spheres deserves to rank as one of the most important: for, should it hereafter be found correct, the advantages resulting to the civilized and learned world, must cause it to stand pre-eminent among the improvements in philosophy. The habitable superfices of our sphere would not only be nearly doubled; but the different spheres of which our earth is probably constituted, might increase the habitable surface ten-fold. That such may be the construction of the earth, every law of matter with which I am acquainted, seems to admit, at least of the possibility; the different appearances of the other planets render it probable; and the various concurring terrestrial facts existing in the arctic regions, to my mind, render such a conclusion almost certain. And further, that matter and space are never uselessly wasted, is an axiom, not only of sound philosophy, but of natural religion, and of common sense. Many of the theories which have been advanced respecting the earth, are vague and uncertain, and will remain so forever; being predicated on deductions drawn from certain premises that can never be established with certainty; consequently they must rest wholly on the strength of the arguments drawn from the premises, as they are not susceptible of being demonstrated by experiment. Not so with the theory of concentric spheres. Its correctness admits of ocular demonstration. The interior of the sphere is declared accessible, and the whole extent capable of being accurately explored; thereby establishing the theory, or disproving and putting it at rest forever.