Improved pump

According to the invention, there is provided a pump comprising: a liquid piston Stirling engine having fluidly connectable first and second columns to contain a working liquid to a variable liquid level, the second column comprising first and second legs at least in part delimiting a variable volume to contain a working fluid; and a pump chamber fluidly connectable to the liquid piston Stirling engine such that a fluid pressure within the pump chamber is variable in response to a variation of the variable liquid level, the pump chamber comprising a weir over which a liquid to be pumped is spillable by the variation of the fluid pressure to inhibit back-flow, through the pump chamber, of the liquid to be pumped. The pump may move the liquid to be pumped in the absence mechanical fluidic valves, e.g. one way valves. In certain embodiments, the pump chamber may be fluidly connectable to the first column and the variable liquid level may be a liquid level of the first column. The first column may be an output column of the liquid piston Stirling engine.