|
|
|||
| |||||||||||||||||||||||||||||||
The spanning of deep rivers and estuaries, the extraction of minerals from wet ground, and the exploration of the continental shelf were possible only when it became feasible for men to work under conditions of increased air pressure. Blacksmiths used leather bellows to generate compressed air as early as the 14th century, and natural philosophers experimented with air pumps in the 16th and 17th centuries, but these hand-powered devices could not conveniently compress the large volume of air needed to provide a practical work space. In the third decade of the 19th century, when engineers developed air pumps powered by
HOME | SUBSCRIBE | SEARCH | CURRENT ISSUE | PAST ISSUES | COLLECTIONS | PRIVACY | TERMS OF USE | HELP | beta.nejm.org Comments and questions? Please contact us. The New England Journal of Medicine is owned, published, and copyrighted © 2009 Massachusetts Medical Society. All rights reserved. |