Regarding the working out of delta month by month, not only are discharges more or less doubtful, but the area irrigated is seldom correct till near the end of the crop. However, the figures, towards the end of a crop, may be useful. If delta on any distributary is higher than is usual on that distributary, it may be desirable, if the supply in the whole canal is short, to reduce the supply to that distributary somewhat, but this remedy can be properly applied after the end of the crop by altering the turns (Art. 5). Any steps in the direction of altering outlets can only be taken after the end of the crop. Admitting, however, that the working out of delta during the crop is useful, it can be done by adding up the gauge readings for the month and taking the average reading and the discharge corresponding to it. This is not quite the same as the average of the daily discharges, but the difference is small, and there would be a wholesale and most salutary saving in clerical work. All the columns headed D could be omitted. The handiness and compactness of the register would be vastly increased. The discharges are only approximately known, and refinements of procedure are unnecessary. The correction of the discharge table, by means of observed discharges, once a month, can of course be effected without booking the daily discharges.[27] [27] There should, in any case, be a special place in the gauge register for showing the discharge tables, with a note of the discharge observations from which the table was framed or in consequence of which it was altered. Supposing the columns D to be retained the calculations of delta can be made as shown in table II. the form being printed in the gauge book. To facilitate the adding up of the discharges a line can be left blank in table I. after each ten days, and the total for the ten days shown on it. If the column D is not retained, the gauge readings can be added up. The discharge corresponding to the mean gauge reading of the month, multiplied by the number of days the distributary was in flow, gives the figure to be entered in column 2 of table II. The final working out of delta crop by crop is of course of the greatest value. The point which needs attention is, as already remarked, greater accuracy in the discharges. For reasons which have already been given (CHAP. I., Art. 5, and CHAP. II., Art. 9) the values of delta on different distributaries will never be the same, but the causes of high values can always be investigated and, to some extent, remedied. TABLE II.--CALCULATION OF DELTA FOR RABI, 1912-13, NANGAL DISTRIBUTARY.