1. A weld metal cooling rate indication system for a welding machine wherein the welding machine has a torch which is capable of producing a weld bead and has a speed sensor which senses the speed at which the torch travels as selected by an operator, the indication system comprising: means for continuously sensing a temperature versus distance profile curve along the weld bead, said profile curve including a predetermined weld temperature; means responsive to the temperature versus distance profile curve sensing means and the speed sensor for calculating and producing a signal which represents rate of change of weld temperature at said predetermined weld temperature along the weld bead; means for producing signals which are representative of a range of acceptable rates of change of weld temperatures at said predetermined weld temperature; means responsive to the calculating means and the producing means for comparing the rate of change of temperature signal with a range of acceptable rates of change of weld temperature signals and producing signals which represent whether the rate of change of temperature is within, above, or below the said range; and means responsive to the comparing means for indicating whether the rate of change of weld temperature is within, above, or below the range of acceptable rates of change of weld temperatures.