nautilus

[Lat., from Gr. nautilos a sea man, a nautilus; nautes a sailor; naus =a ship; Gr. nautile; Ital. & Sp. nautilo.] I. Ord. Lang.: A name popularly applied to two very different animals: the Paper Nautilus-the Nautilus of poets, which belongs to the genus Argonaut a (q. v.), and not to Nautilus [II. 1,2]; and to the Pearly Nautilus ( Nautilus pompilius ), for a long period the only known species. The quotation refers to the Paper Nautilus. II. Technically : 1. Zool .: The typical and only recent genus of the family Nautilide (q. v.). The shell is involute, with an outer porcellanous and an inner nacreous layer. The soft structures of the animal were first described by Owen in 1832, and its anatomy is elaborately discu ed by E. Ray Lankester in the Encyclo pædia Britannica (ed. 9th, art. Mollusca). Three species are known: Nautilus pompilius (the Pearly Nautilus), V. mac rom phil us , and N. umbilicatus , all from the Indian and Pacific Oceans. 2. Paleontology: Range in time from the Upper Silurian to the present day, with a maximum development in the Carboniferous period. 3. Hydraul. Engin .: A form of diving-bell requiring no suspension. Water admitted through the cock into pipes flows into the exterior chambers, causing the apparatus to sink. The workmen enter through an aperture at the top, closed by an airtight cover, and can in still water move the machine in any required direction by stepping on the ground and pushing. Air is condensed in a reservoir at the surface to a degree somewhat greater than the condensation due to the depth, and pa es through a pipe into the chambers rendering the machine specifically lighter than water, and enabling it to lift stones or other objects below. A gauge indicates the amount of lifting power attained as the air is admitted, so that the supply may be cut off when the requisite power is reached.