ignition of the power source other sources of power such as batteries a downhole source of power a mechanical source of power or similar sources of power are also usable such that a electrical connection between the firing head 17 and the surface 16 is not required referring now to fig2 an embodiment of the present power source 21 is shown disposed within the firing head 17 the power source 21 is shown including a quantity of thermite 23 partially encased by a polymer 25 the polymer 25 defining a bottom wall 31 and a side wall 33 in one or more embodiments of the invention the bottom wall 31 and or the side wall 33 can be omitted and the thermite 23 can be pressed against a stop or wall within the firing head 17 or against the setting tool 15 the top of the thermite 23 is shown enclosed by a cap 41 the firing head 17 can also include an outer cap 42 which is shown enclosing the power source 21 contained within enabling the entirety of the pressure produced by the power source 21 to be contained for actuating a movable member shown as a piston 43 within the setting tool 15 by directing the pressure produced by the power source 21 in a downhole direction a thermal generator 27 is shown disposed in contact with the thermite 23 for initiating the thermite reaction an electrical conduit such.