first place, as I pointed out in Invisible Barrier (p. lM), there are secondary factors, such as the variations in crop conditions and technological advance, which must be added to the primary curve of the investment and profit cycle. I n the second place, in the sentence quoted by Mr. Price from Burns and Mitchell, those authors must, especially in view of their own chart, have meant by the sine curve the simple y = a sin x, whereas in my paper in SCIENCE it is obvious, from my equations and

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... e sentence following them, that I was not using the term sinusoidal in the same simple sense, but rather in the sense of a curve oscillating in the manner of a sine curve.