1831 introductions

wave that remains in a constant position

saline water for medical purposes

thumb|Doorbell at the entrance of Chetham's Library, Manchester, England thumb|Sound of a two-tone mechanical doorbell A doorbell is a signaling device typically placed near a door to a building's entrance. When a visitor presses a button, the bell rings inside the building, alerting the occupant to the presence of the visitor. Although the first doorbells were mechanical, activated by pulling a cord connected to a bell, modern doorbells are electric, operated by a pushbutton switch. Modern doorbells often incorporate intercoms and miniature video cameras to increase security.

critical edition of the complete works of Aristotle edited by the philologist August Immanuel Bekker

Brown sauce by Kraft Heinz