Hayek On Reswitching

"...the amount of waiting involved in a particular investment is not simply proportional to the length of the investment period and the value of the input invested, but is dependent also on the rate of interest. In consequence, when we compare two different investment structures, it will not always be possible even to say, on purely technical grounds, which of them involves the greater amount of waiting. At one set of relative values for the different kinds of input and at one rate of interest, the one structure, and at a different set of values or a different rate of interest, the other structure, will represent the greater amount of waiting, or will be 'longer' in the sense in which this term has commonly been used." -- F. A. Hayek (1941). The Pure Theory of Capital, University of Chicago Press: 144

I know about this quotation from Roger W. Garrison's article "Reflections on Reswitching and Roundaboutness".