Abstract: An apparatus and method includes positioning a string in a wellbore, the string having a surge chamber. A closure member is provided below the well surface, with the surge chamber defined at least in part by the closure member. At least one port to the chamber is opened to create a fluid surge into the surge chamber and a local low pressure condition in a wellbore region.

Abstract: An improved bell is disclosed which features a clapper continuously adjustable for hardness of strike. The clapper comprises a hard inner member and a resilient outer member. The periphery of the clapper is circular but the hard inner member is not circular about the same center as the periphery so that the amount of resilient material between the solid inner core member and the periphery varies circumferentially around the clapper. At the time of manufacture of the bell it is tested to locate the point on the bell body at which "wow and flutter" in the tone emitted by the bell is minimized. A single insulated pin serves to orient the handle of the bell, the bell body and the plane of swing of the clapper. The attachment of the handle, the bell body and the clapper is such as to minimize extraneous noise. An elastomer clapper shaft is employed, and its effective flexing length may be varied.