Abstract: An apparatus includes: a fluid container; a fluid mixture disposed within the fluid container, the fluid mixture including at least two components having different relative dielectric constants or different relative permeabilities; an imparter for imparting an electrostatic or electromagnetic force across the fluid mixture to cause at least one of the components to be placed in motion; and a controller for controlling the electrostatic or electromagnetic force to counteract the effects of an applied acceleration. A method includes positioning a high dielectric or high permeability element suspended in a low dielectric or low permeability fluid contained between a pair of charged electrode plates or a magnetic gap; determining a change in capacitance or inductance of the apparatus; and determining from the capacitance change or inductance change a magnitude of the acceleration.

Abstract: An apparatus for determining a trajectory of a directional drill includes two length measurement devices deployed along a surface of the drill string and a controller capable of determining the heading of the drill string from two lengths of the drill string measured by the two length measurement devices. A method includes determining at least two lengths along a surface of a drill string; and determining a heading of the drill string using the at least two determined lengths.