Hydrostatics and pneumatics / [Dionysius Lardner].

  • Dionysius Lardner
Date:
1831
Catalogue details

Licence: Public Domain Mark

Credit: Hydrostatics and pneumatics / [Dionysius Lardner]. Source: Wellcome Collection.

    362/376 (page 346)
    The Diving Bell. (173.) The spirit of enquiry which so strongly cha- racterises the human mind, and which stimulates man to undertakings in which life itself is imminently risked, has not only prompted him to ascend into the regions of the air, but has also carried him to the depths of the sea. The practice of diving is of very early origin, and was first probably adopted for the recovery of articles of value dropped into the water at small depths. Instances are recorded of persons having acquired by practice the habit of enduring submersion for a length of time, which in many cases seems astonishing, and in others altogether incredible. Indeed, the circumstances attending most of these narrations bear unequivocal marks of fiction. The gratification of a taste for the marvellous does not tempt us to allow a space in our pages for a description of the feats of the Sicilian diver, whose chest was so capa- cious that by one inspiration he could draw in sufficient air to last him a whole day, during which time he would sojourn at the bottom of the sea, and who became so inured to the water, that it was almost a matter of indifference to him whether he walked on dry land or swam in the deep, remaining often for five days in the sea, living upon the fish which he caught! Various attempts were made to assist the diver by enabling him to carry down a supply of air; and after a long period and gradual improvements, suggested by experience, the present diving-bell was produced. This machine depends for its efficacy 011 that quality in air which is common to all material substances, impe- netrability; that is, the total exclusion of all other bodies from the space in which it is present. The diving-bell is a large vessel closed at the sides and at the top, but open at the bottom. It should be perfectly impenetrable to air and water. When such a machine, with its mouth downwards, is pressed into the water by sufficient weights suspended from it, the air contained in it at the surface will be enclosed by the sides, the top, and the surface of