I believe the answer that you're looking for is temperature probe. As you raise the heat of the metal cylinder by a specific, measured number of degrees Celsius, you also record the amount of energy put out by the heat source. Specific heat of a substance is equal to the amount of energy or heat needed to raise a substance by one degree Celsius. Use the equation Q=cmΔT, where Q is heat/energy added, c is the specific heat, m is the mass of the cylinder, and ΔT is the change in temperature of the cylinder.