(5) A Glass-Cutter's Knife. This is best made out of a fine three-cornered file, with the file teeth almost ground out, but not quite; it should be about 2 inches long. After the surface has been ground several times, it may be necessary to reharden the steel. This is best done by heating to a full red and quenching in mercury. The grindstone employed for sharpening the knife should be "quick," so as to leave a rough edge. I have tried many so-called glass knives "made in Germany," but, with one exception, they were nothing like so good as a small French or Sheffield file. In this matter I have the support of Mr. Shenstone's experience. (6) A wire nail, about 2 inches long, mounted very accurately in a thin cylindrical wooden handle about 5 inches long by one-quarter of an inch diameter, or, better still, a bit of pinion wire 6 inches long, of which 1.5 inches are turned down as far as the cylindrical core, An old dentists' chisel or filling tool is also a very good form of instrument. (7) A bit of charcoal about 3.5 inches long and 2 wide, and of any thickness, will be found very useful in helping to heat a very large tube. The charcoal block is provided with a stout wire handle, bent in such a manner that the block can be held close above a large glass tube on which the flames impinge. In some cases it is conveniently held by a clip stand. By the use of such a slab of charcoal the temperature obtainable over a large surface can be considerably increased. I have seen a wine-glass (Venetian sherry-glass) worked on a table with four blow-pipes, such as is here described, with the help of a block of hard wood held over the heated glass, and helping the attainment of a high temperature by its own combustion. (8) Several retort stands with screw clips. (9) Some blocks of wood about 5" X 2" X 2" with V-shaped notches cut in from the top. (10) A strong pair of pliers. (11) An apparatus for cleaning and drying the breath, when blowing directly by the mouth is not allowable. The apparatus consists of a solid and heavy block of wood supporting a calcium-chloride tube permanently connected with a tube of phosphorus pentoxide divided into compartments by plugs of glass wool. Care should be taken to arrange these tubes so as to occupy the smallest space, and to have the stand particularly stable. The exit tube from the phosphorus pentoxide should be drawn down to form a nozzle, from, say, half an inch to one-eighth of an inch in diameter, so as to easily fit almost any bit of rubber tube. The entry to the calcium chloride should be permanently fitted to about a yard of fine soft rubber tubing, as light as possible. The ends of this tube should terminate in a glass mouthpiece, which should not be too delicate.