I think, however, that there are various methods by which a hieroglyphic might be formed, whose meaning would be perfectly “hidden;” and I shall give one or two examples of what I consider such. A method which I have adopted for my own private use, is one which I am satisfied is of this nature, as it cannot possibly be solved without the assistance of its key, and that key, by which _alone_ it can be unlocked, exists only in my mind; at the same time it is so simple, that with the practice in it which I have had, I now read it, and write it, with as much facility as I can the English character. As I prefer not giving it here, I shall be compelled to have recourse to some other plan that is more complicated. By a CRYPTOGRAPH, I understand—a communication which, though _clearly_ ascertained by means of its proper key, cannot possibly be without it. To most persons, who have not thought much upon the subject, an article written in simple cipher, (by which I mean with each letter uniformly represented by a single distinct character,) would appear to be an impenetrable mystery; and they would doubtless imagine that the more complicated the method of constructing such a cipher, the more _insoluble_—to use a chemical expression—would be the puzzle, since so much less would be the chance of discovering its key. This very natural conclusion is, however, erroneous, as it is founded on the supposition that possession must first be obtained of the key, in order to unravel the difficulty,—which is not the case. The process of reasoning employed in resolving “secret writing” has not the slightest relation to the form or description of the characters used, but refers simply to their succession, and to a comparison of words in which the same letters occur. By these means any cipher of this nature can be unriddled, as experience has fully shown. A very successful method of avoiding detection, would be to apply the simple cipher to words written backwards and continuously. This, I conceive, might be called a perfect cryptograph, since from the want of spaces, and consequently the impossibility of comparing words, it would utterly perplex the person attempting to discover its hidden import, and yet with the help of the key, each letter being known, the words could easily be separated and inverted. I give a short specimen of this style, and would feel much gratified with your opinion of the possibility of reading it. [Illustration: a cryptograph]