Visualised Numerals

I HAVE lately been occupied in eliciting the degree and manner in which different persons possess the power of seeing images in their mind's eye, and am collecting a large and growing store of materials, partly of verbal answers made by friends to my inquiries, but principally by means of written replies to a printed list of questions that I am distributing. The subject bears in many ways upon psychological and ethnological studies, and I should be glad if the present memoir upon one particular branch of it should induce correspondents to furnish me with authentic information of the kind I seek.