A description is given of the means by which certain difficulties in experimental technique can be overcome. The construction and starting up of the apparatus in such a way as to avoid breakage of the boiling tube is described, and also the making and suspension of the radiation shield, and the general operation of the apparatus. The calculation of the resistance at 444.6 °C. is discussed. Geometrical proofs are given for the relations from which the resistance at 100 and 444.6 °C. are calculated, and special emphasis is laid upon the difference between the two formulas. The effect of errors in readings on the evaluation of δ have been computed for a 10 ohm and a 32 ohm thermometer, and are shown diagrammatically. It is pointed out that errors in measurements of resistance at the steam point and the ice point are of far greater importance than errors in the measurements at the boiling point of sulphur. The conclusion is reached that with the present equipment one must not look for accuracy beyond the third decimal place in the value of δ.