A mathematician writes …

From the preface to Introduction to the Theory of Fourier Integrals, Titchmarsh:

A great variety of applications of Fourier integrals are to be found in the literature, often in the form of `operators’, and often in the works of authors who are evidently not specially interested in analysis. As exercises in the theory I have written out a few of these applications as it seemed to me that an analyst should. I have retained, as having a certain picturesqueness, some references to `heat’, `radiation’, and so forth; but the interest is purely analytical, and the reader need not know whether such things exist.