the average load for the whole year is 3.7 per cent. of the maximum demand on you for current at any one time during that period; or, to put it in another way, this load factor of 3.7 per cent. would show that your investment is in use the equivalent of a little over 323 hours a year on this class of business.  This is by no means an extreme case.  You can find in almost every large city customers whose load factors are not nearly as favorable to the operating company, their use of your investment being as low as the equivalent of 75 or 100 hours a year.  Take another class of business, that of the haberdasher, or small fancy goods store.  As a rule these stores are comparatively small, with facilities for getting a large amount of natural light and little use for artificial light.  The load factor as shown by the chart is about 7 per cent., the use of your investment being not quite twice as long as that of the office building.  Day saloons show an average of 16 per cent. load factor; cafetiers and small lunch counters about 20 per cent., while the large dry goods stores, in which there is comparatively little light, have a load factor of 25 per cent. and use your investment seven times as long per year as the office building.  Power business naturally shows a still better load factor, say 35 per cent., and the all-night restaurant has a load factor of 48 per cent.

You will see from this that the great desideratum of the central station system is, from the investors’ point of view, the necessity of getting customers for your product whose business is of such a character as to call for a low maximum and long average use.  This question of load factor is by all means the most important one in central station economy.  If your maximum is very high and your average consumption very low, heavy interest charges will necessarily follow.  The nearer you can bring your average to your maximum load, the closer you approximate to the most economical conditions of production, and the lower you can afford to sell your current.  Take, for instance, the summer and winter curves of the Chicago Edison company.  The curve of December 20, 1897, shows a load factor of about 48 per cent.; the curve of May 2, 1898, shows a load factor of nearly 60 per cent.  Now, if we were able in Chicago to get business of such a character as would give us a curve of the same characteristics in December as the curve we get in May; or, in other words, if we could improve our load factor, our interest cost would be reduced, an effect would be produced upon the other items going to make up the cost of current, and we probably could make more money out of our customers at a lower price per unit than we get from them now.