An engineer in the power industry

When I first went to the New York Edison Company in 1895, I became very much interested in the study of all factors that influence the cost of production. As an illustration of such interest I have, among my papers, a duration curve entitled “Curve Showing Number of Hours During Which the Load on Duane Street Station Did Not Exceed a Given Percentage of the Annual Maximum Load — Year 1895.” In a marginal tabulation are given, in percentages of the annual maximum, the hours´ use of the station under different loads. The load was greater than 70 per cent of the maximum for less than 1 per cent of the time. For nearly 50 per cent of the time the load did not exceed 6½ per cent of the maximum. Accompanying the curve follows a report of three weeks´ tests to determine the cost of operation for different watches, and the remark is made that by increasing by 50 per cent the output of the minimum watches, the increased output could be produced at one-fifth of the average pounds of coal per kilowatt-hour consumed during the minimum-load watch. I do not believe that a duration curve of the operation of a central station had ever been assembled before. From the broad economic point of view its importance is just as great today as it was in 1895. Upon its underlying principles has been built the structure of efficient operation of plant, economic utilization of investments, and promotional rate schedules.