The pattern or “Form” in which the numerals are seen is by no means the same in different persons, but assumes the most grotesque variety of shapes, which run in all sorts of angles, bends, curves, and zigzags as represented in the various illustrations to this chapter.  The drawings, however, fail in giving the idea of their apparent size to those who see them; they usually occupy a wider range than the mental eye can take in at a single glance, and compel it to wander.  Sometimes they are nearly panoramic.

These Forms have for the most part certain characteristics in common.  They are stated in all cases to have been in existence, so far as the earlier numbers in the Form are concerned, as long back as the memory extends; they come into view quite independently of the will, and their shape and position, at all events in the mental field of view, is nearly invariable.  They have other points in common to which I shall shortly draw attention, but first I will endeavour to remove all doubt as to the authenticity and trustworthiness of these statements.

I see no “Form” myself, and first ascertained that such a thing existed through a letter from Mr. G. Bidder, Q.C., in which he described his own case as a very curious peculiarity.  I was at the time making inquiries about the strength of the visualising faculty in different persons, and among the numerous replies that reached me I soon collected ten or twelve other cases in which the writers spoke of their seeing numerals in definite forms.  Though the information came from independent sources, the expressions used were so closely alike that they strongly corroborated one another.  Of course I eagerly followed up the inquiry, and when I had collected enough material to justify publication, I wrote an account which appeared in Nature on 15th January 1880, with several illustrations.  This has led to a wide correspondence and to a much-increased store of information, which enables me to arrive at the following conclusions.  The answers I received whenever I have pushed my questions, have been straightforward and precise.  I have not unfrequently procured a second sketch of the Form even after more than two years’ interval, and found it to agree closely with the first one.  I have also questioned many of my own friends in general terms as to whether they visualise numbers in any particular way.  The large majority are unable to do so.  But every now and then I meet with persons who possess the faculty, and I have become familiar with the quick look of intelligence with which they receive my question.  It is as though some chord had been struck which had not been struck before, and the verbal answers they give me are precisely of the same type as those written ones of which I have now so many.  I cannot doubt of the authenticity of independent statements which closely confirm one another, nor of the general accuracy of the accompanying sketches, because I find now that my collection is large enough for classification, that they might be arranged in an approximately continuous series.  I am often told that the peculiarity is common to the speaker and to some near relative, and that they had found such to be the case by accident.  I have the strongest evidence of its hereditary character after allowing, and over-allowing, for all conceivable influences of education and family tradition.