In this study, we show how, to yield the real cost of borrowing, the price level can be combined with the nominal interest rate in a monetary regime where the level of prices is trend stationary. We show that the price level then conveys intertemporal information in a way similar to nominal interest rates. We estimate real interest rate series for the gold-standard period in the United Kingdom under the assumption the agents expect the price level to come back to its long-run equilibrium value. The positive correlation between the price level and the nominal interest rate-known as the Gibson paradox and far from being paradoxical-helps explain why the nominal interest rate was so stable in a period characterized by numerous wars and important gold discoveries. The new real interest rate series provides the opportunity to re-examine Barro's (1987) finding on the effect of temporary military spending on interest rates. It also relaxes the assumption that the nominal long-term interest rate is also the expected real rate.