Dash-Pot

A cylinder and piston, the latter loosely fitting or perforated, or some equivalent means being provided to permit movement. The cylinder may contain a liquid such as glycerine, or air only. Thus the piston is perfectly free to move, but any oscillations are damped (see Damping). In some arc lamps the carbon holder is connected to a dash-pot to check too sudden movements of the carbon. The attachment may be either to the piston or to the cylinder. In the Brush lamp the top of the carbon holder forms a cylinder containing glycerine, and in it a loosely fitting piston works. This acts as a dash-pot.