From these reflections I returned to the objects on the table. The spectacles, as things of which I had some expert knowledge, were not so profound a mystery to me. A pair of spectacles might easily afford good evidence for identification; that I perceived clearly enough. Not a ready-made pair, picked up casually at a shop, but a pair constructed by a skilled optician to remedy a particular defect of vision and to fit a particular face. And such were the spectacles before me. The build of the frames was peculiar; the existence of a cylindrical lens⁠—which I could easily make out from the remaining fragments⁠—showed that one glass had been cut to a prescribed shape and almost certainly ground to a particular formula, and also that the distance between centres must have been carefully secured. Hence these spectacles had an individual character. But it was manifestly impossible to inquire of all the spectacle-makers in Europe⁠—for the glasses were not necessarily made in England. As confirmation the spectacles might be valuable; as a starting-point they were of no use at all.