A mode of corresponding by the touch has been suggested by M. Haüy, and by this means the blind have been fully instructed, not only in the rudiments of language, but also in the liberal arts and sciences. M. Haüy's method of preparing the books, &c., which is simple and easy of attainment, is as follows: when the types have been arranged and fixed, a page of very strong paper is moistened, so as to be capable of receiving and retaining impressions, and laid upon the types; and then by the operation of a press or hammer, frequently repeated over the surface, the impression of the type is made to rise on the opposite side of the paper; and it continues, when dry, not only "obvious to the sight," but to the touch, and is not easily effaced. On the upper side of the paper, the letters appear in their proper position; and by their sensible elevation above the common surface, the blind may easily read them with their fingers. For epistolary correspondence it will be necessary to moisten the paper and use a metal pen. No. XLIII. How to vary each of these, so that ten thousand may know them, and yet keep the understanding part from any but their correspondent. NOTE. This may be effected by changing the order of their arrangement, which can only be ascertained by a previous examination of a key chosen for that purpose. No. XLIV. To make a key of a chamber door, which to your sight hath its wards and rose-pipe but paper thick, and yet at pleasure, in a minute of an hour, shall become a perfect pistol, capable to shoot through a breastplate, commonly of carabine proof, with prime, powder, and fire-lock, undiscoverable in a stranger's hand. NOTE. The _rose-pipe_ must in this case be formed like the sliding tubes of a telescope; that next the wards being furnished with a screw at the inner and capable of holding the whole of them together. A small quantity of detonating powder being first placed within, the pipe may be readily discharged by tightening of the screw. No. XLV. How to light a fire and a candle, at what hour of the night one awaketh, without rising or putting one's hand out of bed. And the same thing to be a serviceable pistol at pleasure; yet, by a stranger, not knowing the secret, seemeth but a dexterous tinder-box. NOTE.