Operating expenses $ 67 Fixed charges $ 28 ---- $ 95 Leaving profit $ 5 ---- Total $100 A positive decline of ten per cent, in the tonnage, if the cost for operation per unit of the portion lost was the same as the rest, would obviously reduce the operating expenses also by ten per cent. Let it next be assumed, as was done previously, that the average extra cost per unit of the latest increment of business was only forty per cent. as much as for the remainder of the tonnage. How closely this will approximate the facts in any particular instance will depend upon the density of traffic attained in relation to the capacity of the existing plant. If the addition of the last ten per cent. of business did not increase the large proportion of fixed expenses at all, and only added forty per cent. per unit more to the variable expenses; per contra, the loss of it would merely reduce the variable expenses and still leave the constant outlay the same. On this assumption, by the loss of ten per cent. of business the total amount of operating expenses under the new conditions would be lessened, not by ten per cent. of $67, but by only forty per cent. of ten per cent. of $67. The income would, however, decline by the full amount of ten per cent. The account, after a loss of ten per cent. of business, would then stand somewhat as follows: Operating expenses ($67 less forty per cent. of ten per cent. of $67) $64.32 Fixed charges, as before $28.00 ------ $92.32 Income, reduced by ten per cent. $90.00 ------ Leaving a deficit of $2.32 Or, in other words, a decline of ten per cent. in tonnage has transmuted a five per cent. dividend condition into one involving an actual deficit nearly half as great as the former profit. The sudden reversal from apparent prosperity to very real distress, such as occurred during the fall of 1907, is thus explained. Its suddenness may be shown by the following table of monthly gross and net earnings, promulgated by the Interstate Commerce Commission.[53] The acute panic occurred during October, but its effect was not apparent until the following month. The total mileage included is shown by the first column: