(3) To make another type of simple fuse, soak one end of a piece of string in grease. Rub a generous pinch of gunpowder over the inch of string where greasy string meets clean string. Then ignite the clean end of the string. It will burn slowly without a flame (in much the same way that a cigarette burns) until it reaches the grease and gunpowder; it will then flare up suddenly. The grease-treated string will then burn with a flame. The same effect may be achieved by using matches instead of the grease and gunpowder. Run the string over the match heads, taking care that the string is not pressed or knotted. They too will produce a sudden flame. The advantage of this type of fuse is that string burns at a set speed. You can time your fire by the length and thickness of the string you chose. (4) Use a fuse such as; the ones suggested above to start a fire in an office after hours. The destruction of records and other types of documents would be a serious handicap to the enemy. (5) In basements where waste is kept, janitors should accumulate oily and greasy waste. Such waste sometimes ignites spontaneously, but it can easily be lit with a cigarette or match. If you are a janitor on night duty, you can be the first to report the fire, but don’t report it too soon. (6) A clean factory is not susceptible to fire, but a dirty one is. Workers should be careless with refuse and janitors should be inefficient in cleaning. If enough dirt and trash can be accumulated an otherwise fireproof building will become inflammable. (7) Where illuminating gas is used in a room which is vacant at night, shut the windows tightly, turn on the gas, and leave a candle burning in the room, closing the door tightly behind you. After a time, the gas will explode, and a fire may or may not follow. (b) _Water and miscellaneous_ (1) Ruin warehouse stock by setting the automatic sprinkler system to work. You can do this by tapping the sprinkler heads sharply with a hammer or by holding a match under them. (2) Forget to provide paper in toilets; put tightly rolled paper, hair, and other obstructions in the W. C. Saturate a sponge with a thick starch or sugar solution. Squeeze it tightly into a ball, wrap it with string, and dry. Remove the string when fully dried. The sponge will be in the form of a tight hard ball. Flush down a W. C. or otherwise introduce into a sewer line. The sponge will gradually expand to its normal size and plug the sewage system. (3) Put a coin beneath a bulb in a public building during the daytime, so that fuses will blow out when lights are turned on at night. The fuses themselves may be rendered ineffective by putting a coin behind them or loading them with heavy wire. Then a short-circuit may either start a fire, damage transformers, or blow out a central fuse which will interrupt distribution of electricity to a large area.