1 Note that the speed at which a particular temperature (such as the melting point of wax) travels along a bar when one end is heated is essentially the speed of the 'temperature waves'. This involves specific heat capacity and density as well as conductivity. Thus a rod of lead makes a quick start in the race although it is a poor conductor, but the wax-melting will not have travelled far when a steady state is attained.
2 The experiment involves heat losses from the surface of the rod. If for a steady state, the distance from the heated end to the melting point of the wax is twice as great for rod A as for rod B, then rod A has only half the temperature gradient but twice the surface area for heat losses. So rod A must have four times the conductivity of rod B.
3 The versions of this apparatus currently available are of the static warm water type. The preferred form has steam passing continuously through the apparatus. This is left to attain a steady state. Slider rings indicate the progress of the melting wax.
This experiment was safety-checked in January 2007