TO ALL THE WORLD!
I declare the earth is hollow and habitable within; containing a number of solid concentrick spheres, one within the other, and that it is open at the poles 12 or 16 degrees; I pledge my life in support of this truth, and am ready to explore the hollow, if the world will support and aid me in the undertaking.
Jno. Cleves Symmes.
Of Ohio, Late Captain of Infantry.
N. B. — I have ready for the press, a Treatise on the Principles of Matter, wherein I show proofs of the above positions, account for various phenomena, and disclose Doctor Darwin’s Golden Secret.
My terms are the patronage of this and the new worlds.
I dedicate to my Wife and her ten Children.
I select Doctor S. L. Mitchill, Sir H. Davy, and Baron Alex. de Humboldt, as my protectors.
I ask one hundred brave companions, well equipped, to start from Siberia in the fall season, with Reindeer and slays, on the ice of the frozen sea: I engage we find a warm and rich land, stocked with thrifty vegetables and animals if not men, on reaching one degree northward of latitude 82; we will return in the succeeding spring. J. C. S.
In 1818, this small pamphlet, simply titled ‘Circular Number 1’, was disseminated across the United States by John Cleves Symmes, Jr., a former Captain in the US cavalry, a self-styled natural philosopher, and ostensibly not insane. This last element is by virtue of the certificate included with Circular Number 1 to ensure that it would not be dismissed at the ravings of a lunatic. Though the idea of a hollow earth with concentric spheres has been in place since the late Seventeenth century, and influenced earlier hollow earth narratives (that were more likely to take a Swiftian tone with their ‘findings’) the Symmes theory is unique for its influence on American science, politics and literature.
What is meant by terra cava? I use this term to encompass the variety of ‘hollow earth’ literature that includes semi-hollow earth novels (those that employ vast caverns and cave systems), interior concentric spheres, and the Nineteenth century concept of a hollow earth open at the Poles.
 David Standish, Hollow Earth: The Long and Curious History of Imagining Strange Lands, Fantastic Creatures, Advanced Civilizations, and Marvelous Machines Below the Earth’s Surface. (Cambridge, MA: Da Capo Press, 2006), pp. 40-1.
 Peter Fitting, Subterranean Worlds: A Critical Anthology. (Middletown, CT: Wesleyan University Press, 2004), p. 95.