The air-bladders of fish are nicely adapted to their intended purpose; for though they render them buoyant near the surface without the labour of using their fins, yet, when they rest at greater depths, they are no inconvenience, as the increased pressure of the water condenses the air which they contain into less space.  Thus, if a cork or bladder of air was immersed a very great depth in the ocean, it would be so much compressed, as to become specifically as heavy as the water, and would remain there.  It is probable the unfortunate Mr. Day, who was drowned in a diving-ship of his own construction, miscarried from not attending to this circumstance:  it is probable the quantity of air he took down with him, if he descended much lower than he expected, was condensed into so small a space as not to render the ship buoyant when he endeavoured to ascend.]

        Her secret vows the Cyprian Queen approves,
410 And hovering halcyons guard her infant-loves;
        Each in his floating cradle round they throng,
        And dimpling Ocean bears the fleet along.—­
        Thus o’er the waves, which gently bend and swell,
        Fair GALATEA steers her silver shell;

415 Her playful Dolphins stretch the silken rein,
        Hear her sweet voice, and glide along the main. 
        As round the wild meandering coast she moves
        By gushing rills, rude cliffs, and nodding groves;
        Each by her pine the Wood-nymphs wave their locks,
420 And wondering Naiads peep amid the rocks;
        Pleased trains of Mermaids rise from coral cells,
        Admiring Tritons sound their twisted shells;
        Charm’d o’er the car pursuing Cupids sweep,
        Their snow-white pinions twinkling in the deep;
425 And, as the lustre of her eye she turns,
        Soft sighs the Gale, and amorous Ocean burns.

        On DOVE’S green brink the fair TREMELLA stood,
        And view’d her playful image in the flood;

[Tremella, l. 427.  Clandestine marriage.  I have frequently observed fungusses of this Genus on old rails and on the ground to become a transparent jelly, after they had been frozen in autumnal mornings; which is a curious property, and distinguishes them from some other vegetable mucilage; for I have observed that the paste, made by boiling wheat-flour in water, ceases to be adhesive after having been frozen.  I suspected that the Tremella Nostoc, or star-jelly, also had been thus produced; but have since been well informed, that the Tremella Nostoc is a mucilage voided by Herons after they have eaten frogs; hence it has the appearance of having been pressed through a hole; and limbs of frogs are said sometimes to be found amongst it; it is always seen upon plains or by the sides of water, places which Herons generally frequent.