T. E. Lawrence Correspondence – Page 666

Remember that we put these candles (one by one) off from a 12 V. .5 amp battery, and a starting battery at that. The snifty little Pain detonators get the surprise of their lives ! They fire equally well if the cotton winding is wholly removed - and no wonder when you ... estimate the reserve of juice behind the switch. I should advise whoever is dealing with the matter to use a "soft" explosive, and very slender leads. If properly joined up and waterproofed, the Pain articles are 95% efficient. The waterproofing is, of course, for the compound and not for the detonator. As for the installation, we have a master-switch, then the eight individual-firing switches, each with two leads to a pair of terminals (insulated in wood) on the ship's deck just ahead of the smoke canister stands. A short length of rubber-covered lead joins these terminals to the cotton-wound leads of the detonators. The heat of the candles burns the last bit of lead, which is the reason why we stop the permanent wiring (from the switches) well short of the candle-stands. Warn the experts not to fix too heavy a lead to their detonators, or the bumbing of the boat will sway they, and perhaps drag ... detonator from its bed in the firing powder.