Page:Incandescent electric lighting- A practical description of the Edison system.djvu/107

 on a variation in load and increase of business. This includes coal, oil, lamp renewals, and small increase from time to time in the amount of labor employed. The fixed expenses include those items which remain practically constant under varying conditions of income. A careful analysis of all the items covered in these expenses in such a station as this one, gives the following result: That the fixed expenses are seventy-five per cent, of the whole, and the variable twenty-five per cent, approximately; or, in language which may appeal more directly to you, if we double our income or business, we only increase our expenses 25 per cent. This shows that a station's possibilities and profit lie in increasing this business from the unit point.

The average income per light in stations of this class varies in different parts of the country and with different loads. We have obtained a load diagram, taken from this station, which gives a fair idea of the changes and variations here taking place. The maximum