The Lace or Girt is made of strong brace-web, after the manner and size of the paper pattern enclosed; the parts marked with ink are to be covered with the glass composition, to be laid on tolerably thick--say the thickness of a three shilling piece, and about an eighth of an inch broad in each place; let it remain until quite dry, and then sew it in like manner as the pattern, and from one to one grain and a half of Fulminating Silver to be enclosed in the part marked S; a piece of paper or silk well pasted on one side is then to be wrapped twice round in the same manner as the paper in the pattern is pinned; a strong lace-hole is then to be worked at each end--the manner of applying it is to hang it on two hooks, one on the door post, and the other on the door, taking care to place the part in such a position as to come in contact with the edge of the door, on its being opened, which will cause an immediate explosion louder than a musket. Hooks may also be placed on windows or shutters, and the Lace being hung on them will produce the same effect: a greater safeguard against midnight intruders has never been discovered. FULMINATING LETTERS. The letter inclosed is a pattern of the manner in which they are put together, an examination of which will give the true idea to every attentive observer: a sheet of paper should be used doubled, and cut according to pattern; two slips of parchment must be used instead of those of paper, as enclosed in the pattern letter. The ends marked with Ink must be slightly covered with glass composition, and about an eighth of an inch wide, they must then be laid separately to dry, and when quite dry they must be sewn at one edge as shewn in the pattern, you must then put one third of a grain of Brugnatelli's Fulminating Silver in between the parts marked S, a piece of coloured paper or ribbon is then to be pasted well on one side, and wound twice round in the same way as the paper is now pinned round. The parchment slips thus prepared, must be pasted at each end for about an inch, and so fastened to the letter marked with a cross; the letter is then to be folded, and no further sealing is required. It must here be observed, that although the pattern is in miniature, the directions here given are intended for a common size letter; all that is required to make it so, being to use longer strips of parchment, taking care that the parchment is always as long as the letter is wide. This letter may be sent to any part of the world, and on its being opened will cause a report nearly as loud as a pistol: it is consequently well adapted to prove a never-failing source of amusement. _FULMINATING_ BALLS & BOMBS.