Pencil detonator
10, Delay" and often referred to as a "timing pencil"), was made of a brass (or in later versions aluminium) tube, with a copper section at one end which contained a glass vial of cupric chloride (the liquid was widely and erroneously reported to be sulfuric acid[original research?
The timer was started by crushing the copper section of the tube to break the vial of cupric chloride, which then began to slowly erode the wire holding back the striker.
Crush the end of the thin copper tube containing the cupric chloride with pliers, or under the heel of your boot.
All that is required is to crush and dent the tube sufficiently to break the glass vial, thereby releasing the liquid contained within.
If the inspection hole is unobstructed (i.e. it is possible to see right through to the other side) then the countdown has started and the brass safety strip (holding back the striker) should be removed and discarded.
However, if the inspection hole is obstructed (before the safety strip is removed) the striker has been released so the pencil detonator should be discarded and another one selected.
The final step is to insert the end of the pencil which has the actual detonator fitted into the explosives and leave the area.
When the starting pin was removed, this wire was placed under tension by the spring-loaded striker, and began to gradually stretch.
When a time pencil of this type fired, it would light the fuse which would burn towards a detonator crimped onto the other end.
For example, a pencil detonator designed to fire 24 hours after being activated could in reality give a 30-hour delay - if the weather was very cold.
The main virtue of pencil detonators is their small size and light weight, plus the fact that they are very quick and easy to use.
Note that if both detonators were going to work, the explosion will occur at the earlier of the two times; thus this method will also slightly reduce the average delay.
His driver, Leutnant Erich Kretz, reported seeing Werner von Haeften throw something into the woods in his mirror.
Time pencils figure in the 1961 war movie The Guns of Navarone when an undercover explosives expert, portrayed by David Niven, finds that his stock has been rendered inoperative.
