[130] If the amount of the sinking fund be reduced, and the annual payment is continued over a greater number of years, the present value--so powerful is the operation of compound interest--cannot be materially increased. A payment of $500,000,000 annually _in perpetuity_, assuming interest, as before, at 5 per cent, would only raise the present value to $10,000,000,000. [131] As an example of public misapprehension on economic affairs, the following letter from Sir Sidney Low to _The Times_ of the 3rd December, 1918, deserves quotation: "I have seen authoritative estimates which place the gross value of Germany's mineral and chemical resources as high as $1,250,000,000,000 or even more; and the Ruhr basin mines alone are said to be worth over $225,000,000,000. It is certain, at any rate, that the capital value of these natural supplies is much greater than the total war debts of all the Allied States. Why should not some portion of this wealth be diverted for a sufficient period from its present owners and assigned to the peoples whom Germany has assailed, deported, and injured? The Allied Governments might justly require Germany to surrender to them the use of such of her mines, and mineral deposits as would yield, say, from $500,000,000 to $1,000,000,000 annually for the next 30, 40, or 50 years. By this means we could obtain sufficient compensation from Germany without unduly stimulating her manufactures and export trade to our detriment." It is not clear why, if Germany has wealth exceeding $1,250,000,000,000. Sir Sidney Low is content with the trifling sum of $500,000,000 to $1,000,000,000 annually. But his letter is an admirable _reductio ad absurdum_ of a certain line of thought. While a mode of calculation, which estimates the value of coal miles deep in the bowels of the earth as high as in a coal scuttle, of an annual lease of $5000 for 999 years at $4,995,000 and of a field (presumably) at the value of all the crops it will grow to the end of recorded time, opens up great possibilities, it is also double-edged. If Germany's total resources are worth $1,250,000,000,000, those she will part with in the cession of Alsace-Lorraine and Upper Silesia should be more than sufficient to pay the entire costs of the war and reparation together. In point of fact, the _present_ market value of all the mines in Germany of every kind has been estimated at $1,500,000,000, or a little more than one-thousandth part of Sir Sidney Low's expectations. [132] The conversion at par of 5,000 million marks overstates, by reason of the existing depreciation of the mark, the present money burden of the actual pensions payments, but not, in all probability, the real loss of national productivity as a result of the casualties suffered in the war.