[Illustration: _Fig. 64._] This structure is shown in Figs. 63 and 64, the former representing the under surface of one of the toes of the natural size, and the latter a toe dissected and highly magnified, to show the appearance of the cavities in its under surface, their fringed edge, the depth of the cavities, and the small muscles by which they are drawn open. The edge of the pockets or cavities is composed of rows of a beautiful fringe which are applied to the surface on which the animal walks against gravity, while the pockets themselves are pulled up by the muscles attached to them, so as to form the cavities into suckers. This structure Sir Everard Home found to bear a considerable resemblance to that portion of the head of the _Echineis Remora_, or sucking-fish, by which it attaches itself to the shark, or the bottoms of ships. This apparatus is shown in Fig. 65: it is an oval form, and is surrounded by a broad loose moveable edge, capable of applying itself closely to the surface on which it is set. It consists of two rows of cartilaginous plates connected by one edge to the surface on which they are placed, the other, on the external edge, being serrated like that in the cavities of the feet of the Gecko. The two rows are separated by a thin ligamentous partition, and the plates, being raised or depressed by the voluntary muscles, form so many vacua, by means of which the adhesion of the fish is effected. [Illustration: _Fig. 65._] These beautiful contrivances of Divine Wisdom cannot fail to arrest the attention and excite the admiration of the reader; but though there can be little doubt that they are pneumatic suckers wrought by the voluntary muscles of the animals to which they belong, yet we would recommend the further examination of them to the attention of those who have good microscopes at their command. LETTER XI. Mechanical automata of the ancients--Moving tripods--Automata of Dædalus--Wooden pigeon of Archytas--Automatic clock of Charlemagne--Automata made by Turrianus for Charles V.--Camus’s automatic carriage made for Louis XIV.--Degenne’s mechanical peacock--Vaucanson’s duck which ate and digested its food--Du Moulin’s automata--Baron Kempelen’s automaton chess-player--Drawing and writing automata--Maillardet’s conjurer--Benefits derived from the passion for automata--Examples of wonderful machinery for useful purposes--Duncan’s tambouring machinery--Watt’s statue-turning machinery--Babbage’s calculating machinery.