CHAMBER, in military affairs. 1. Powder chamber, or bomb chamber, a place sunk under ground for containing the powder or bombs, where they may be out of danger, and secured from the rain. 2. Chamber of a mine, the place, most commonly of a cubical form, where the powder is confined. 3. Chamber of a mortar, that part of the chase, much narrower than the rest of the cylinder, where the powder lies. It is of different forms, sometimes like a reversed cone, sometimes globular, with a neck for its communication with the cylinder, whence it is called a bottled chamber; but most commonly cylindrical, that being the form which is found by experience to carry the shell to the greatest distance.