[11] Imagine an immense sphere enclosed within two contiguous and equally thin envelopes, and yet sufficiently thick to show their edges distinctly when broken; the outer, a photosphere, having an intensely bright surface, and the inner, or penumbra, of a dull gray surface; while the enclosed hollow space is all dark, with the exception of an occasional fleecy cloud, floating within, and contiguous to the inner envelope. Now remove a large irregular piece from the outer, and a smaller piece from the inner envelope, and you have an exact idea of the appearance of a spot; contrasting the comparative brilliancy of the photosphere with the penumbra; their relative thickness; the intense blackness within, and occasional cloud stratum floating beneath the opening, as seen, under the most favorable circumstances, with a good telescope.
[12] The Nasmyth willow-leaf appearance, I think, is either the result of imperfect vision, defective instruments, or unfavorable state of the air, distorting the unvarying result of my observations, as above described, which have been a thousand times repeated in our clearer atmosphere, both on the coast and interior mountain regions. My observation of a general pore-like character, over the whole surface of the photosphere of the sun, is, I think, corroborated by considering the spots, as usually known and visible with ordinary instruments, as merely greater pores of the same general character.
[13] 'Life and Letters of Washington Irving,' by Pierre M. Irving. New York: G. P. Putnam.
[14] Elements of International Law. By Henry Wheaton. Edited by W.B. Laurens. Boston: Little, Brown & Co.
[15] The Federalist. Edited by H. B. Dawson. New York: C. Scribner.
[16] 'Caxtoniana.'