You can contact me at rogercdavies(atsquiggle)  If you have a comment and the system won't let you post it, ping me using the @ for (atsquiggle)

This blog has evolved into a review of historical and modern explosive devices, and responses to them. Links are drawn between historical activity and similar activity in the world today. Mostly I focus on what are now called IEDs but I have a loose personal definition of that and wilingly stray into discussions of more traditional munitions, the science and technology behind them, tactical employment and EOD responses. Sometimes it's just about interesting people in one form or another. Comment is welcome and encouraged but I do monitor it and reserve the right to delete inappropriate stuff. Guest posts are always welcome. Avoid any stuff that makes the enemy's job easier for them.

A note on moral perspectives. Throughout this blog there are descriptions of all sorts of people using IEDs, explosives, or suffering the consequences. Some of the people using IEDs are thought of as heroes by some and terrorists by others. One person's good guy fighting for a cause is another person's evil demon.  It's complicated, and history adds another series of filters too. All of us too live in a narrative made up around however we were brought up, what we were taught and what we learned along the way, rightly or wrongly. So if you sense moral ambivalence, one way or the other, well, I'm guilty and I'm not perfect.  By and large though, I have unapologetic sympathy for those dealing with the devices, whether they be soldiers, cops, or whatever, even those who are part of Nazi or other nasty regimes. That's the cool thing about EOD techs - we don't really care who the enemy is.


Entries in 1700-1800 (11)


A letter bomb defuzed, 1712

Here are some details of a letter bomb sent to the Earl of Oxford in November 1712.  The device was defuzed by the author of "Gulliver's Travels", Jonathan Swift. There was much misreporting of the incident in the newspapers of the time but I have found a reference to what actually happened with some significant detail of the device in a book by Swift which refers to this report as being correct.  In this report, the "gentleman in the room" is Swift.  A bandbox is a box used for storing hats. I believe the "wild-fire" referred to is some sort of flammable oil.


The First Metal Cased Rockets

Over the past few months I have been in conversation with a new Indian friend, Mr Nidhin Olikara.   He has done some tremendous work with archaeological colleagues on some ancient rockets recently discovered from the time of Tipu Sultan, in the late 1700s in India.  These metal cased rockets predate any European metal cased rockets, and were, I believe a source of technology for Congreve’s rockets, developed at Woolwich in England in the early 19th century.  Congreve gave little or no credit to the Indian technology which he exploited, and no credit at all to the Dublin rebels' rockets, which I believe were also inspired by the Indian rocket technology.
This is a complex story of industrial history, archaeology, munitions exploitation, technical intelligence, metallurgy and ordnance design.   For context, I have written before about European rocket development here: 
 and Robert Emmet's rockets in Dublin in 1803 here:
Mr Olikara and his colleagues came across many rockets which appear to have been disposed of down a well. They have been able to recover these and examine them scientifically and the results are fascinating. They have written a paper recently published in the Journal of Arms and Armour Society, Volume 22, No 6, dated September 2018. It is not yet available on-line.  
Rockets were developed in India by the forces of Haider Ali and then his son Tipu Sultan in the late 1700s. They were used extensively against their enemies, including the British. Amongst Tipu Sultan’s allies, were the French, which may be relevant for later parts of this story. It appears that the British recovered some of these metal cased rockets to Woolwich Arsenal. 
Some of the 160 rockets that Mr Olikara recovered have now been analysed and the results are fascinating. A quick summary:
  • a. The rockets are largely of a similar dimension to the (later) first of Congreve's rockets, varying in diameter between about 35mm and 65mm
  • b. They appear to be made of what we would call today “mild steel”. ie relatively low carbon content. This would make the metal relatively malleable.
  • c. The assessment is that the cylinder components of the rocket were hot or cold forged on a cylindrical die or anvil, with two end caps (one with a vent) forged onto the ends. To be clear, the base material is a rectangle of sheet mild steel, hammered on a cylindrical anvil into a tube shape and two flat circles then attached to the ends, by hammering. One of these ends has a central vent acting as a venturi choke.
  • d. Remarkably the contents of the rocket were still largely present and chemical analysis gives results consitstent with gunpowder/blackpowder.  In some rockets there is still a clear suggestion of a formed central combustion chamber formed in the propellant.
  • e. Perhaps most interesting of all, from a munition design perspective is that the rockets appear to have been lined with a refractory element such as clay, providing a layer between the explosive/propellant fill and the steel wall of the rocket. Most intriguing. I can find no reference of a similar fabrication in later Western rockets
What is still unclear is the filling process in relation to the fixing of the end caps. What came first?  Fixing the end caps first makes sense from a safety perspective but makes the filling process tricky. I expect it will depend on the nature of the filling and how easy it was to load it in the cylinder. I suspect that the front end cap was fixed first, and the rear closing cap fitted “snugly" then removed, the rocket then lined with clay, dried, and the powder fill put into place. The combustion chamber would then be bored, the rear cap affixed in some manner (carefully) so as to not ignite the charge, and a fuse made of some sort of cloth inserted in the nozzle/venturi. 
What is also is unclear is how the longitudinal seam of the rockets metal cylinder body was formed. I suspect it was “folded” in a “finger lock seam”. To do this, (and speaking as a very amateur blacksmith), the two sides of the rectangle to be joined would be first turned and folded back a few mm on the edge of an anvil into a lip. When the sheet is then formed into a cylinder these folded turns would interlock.  I will experiment in my own forge in coming days and try to post pictures. 
I think the implications of these findings might be as follows:
  1. The Armies of Haider Ali and Tipu Sultan had an industrial level production firstly of mild steel in sheet form.  I doubt this was “ rolled” steel but was probably very skilfully hammered. what is most significant,  I think, is that the steel was being produced for a “ disposable”, one-time-use system. That indicates that sheet mild steel which heretofore was perhaps an expensive luxury for body armour of the rich and wealthy was available in such quantities in its sheet condition to be economic to make into one-time-use discardable munitions. I think that’s quite significant.          
  2. This was proper industrial scale production of steel components, albeit the rocket diameters seem to vary.  The skills in hot and cold forging mild steel are not dissimilar to the making of protective armour.   The history of technology of India in a broader sense has often been ignored or discounted by the West. India’s metallurgical developments of such things as pure wrought iron, mild steel, carbon steel and Wootz steel is fascinating and the technological processes associated with manufacture of items from these materials seems to have been often ignored in history.  This book published originally in the middle of the 19th century gives some insights into the broad range of military metallurgy in India over a number of centuries.
  3. The technology is well in advance of European rocketry which did not use metal cases (apart from the Emmet rebellion in Dublin in 1803), until 1805. Congreve, a man of his time, was disinclined to give credit to India, Emmet the Irish Rebel or indeed others (a Scotsman also claimed to have sent him the idea of metal cased rockets.)  Congreve was driven of course by the opportunity to make a considerable fortune and reputation. Also, perhaps the role of technical intelligence from one's enemies was, as it still is, always understated.
This development, like all good historical stroies, prompts further questions:
  1. How did the French alliance with Tipu Sultan allow them to obtain metal cased rocket technology and pass such technology down to manufacturing instructions to Emmet in 1802/1803?
  2. Why did the French (at the time renowned for their scientific expertise in military matters) not develop rockets themselves until after Congreve had? French interest approved by Napoleon seems to have started in about 1809. 
  3. What was the level of input into Congreve’s development from Irish rebel Pat Finnerty, Emmet’s rocket maker who ended up working for Congreve at Woolwich in 1804?
  4. What earlier (non-metal cased) rocket experiments at Woolwich by the British artillery general, General Desaguliers was Congreve able to draw on. He would have been aware of these experiments I’m sure, which had occurred some years earlier but were deemed a failure. But much would perhaps have been learned about propellant. 
  5. Was there any technology transfer in the other direction?  Mr Olikara and his team found what I am certain is a rocket boring tool in their investigation, used to bore a combustion chamber in the packed rocket body - it is remarkably similar to tools used in European rocket making in the 1600s…also,   steel rolling mills were developed in Europe in the latter part of the 1700s… is it possible that this technology transferred to India, enabling the production of quantities of sheet steel for the rocket bodies? Or did Tipu Sultan simply reply on a large number of people involved in the manufacture, hammering out sheet steel with such skill?
Mr Olikara has also, interestingly and separately from the paper, found records of what I take to be a British military EOD operation in 1871. The operation involved the disposal (by an Ordnance officer) of cannon from the time of Tipu Sultan (70 years earlier) and mentions finding rockets that were still filled with propellant  from this time. One of the cannon exploded (still loaded from 70 years earlier) while it was being prepared for destruction, killing one man.  So in 1871, Ordnance EOD operations were dealing with dangerous munitions from earlier wars… Plus ca change!
The development of military rockets by Congreve and subsequently by quite a number of European and American nations continued throughout the 19th century, slowing when artillery systems improved, but there was certainly some sort of rocket arms race as Congreve, then Hale developed British rockets systems and the Europeans raced to get ahead.  Even today it is possible to see in very real terms the evolution from Mysorean rockets to Congreve, to Hale and all the way through to say a modern Russian 107mm rocket system - and such systems are being adapted for improvised systems in Syria  and Iraq today with much effect. Military metal-cased rockets are a staple of modern warfare, but now the nature of its origins in India is somewhat clearer. Those wishing more detail should obtain Mr Olikhara’s paper (I may be able to help), and also a book “The First Golden Age of Rocketry by F H Winter is a useful reference.

The language of IEDs

What we now call Improvised Explosive Devices have had different names over the centuries that they have been used. Here's one you may not have heard of.  The word "caisson" has a range of meanings derived from the "sealed box" of its original meaning. Today a caission is associated with either the ammunition box used in support of an artillery piece, or a sealed box like structure sunk in water to allow engineering work to take place.  But in 1778 "caisson" had this meaning, according to a military dictionary published that year:


Clocks, locks, energy and initiation

I’ve written before about the evolution of gunlocks, from matchlocks, through wheel-locks to snap-huances and then flintlocks because although these initiation systems were designed to initiate firearms they also enabled initiation mechanisms for explosive devices.  This post returns to that subject to discuss a couple of more elements to that story that I find interesting, namely engineering development and some fundamental issues about “energy” chains that apply both to these firearms systems and explosive devices.  In this post I have made some generalisations and simplifications in my description of the technology - forgive me, but otherwise the post turns into a book and neither you or I have time for that.                                                                      
Firearm initiation systems, and in parallel explosive initiation systems, are about initiating a quantity of explosives at a time that the operator chooses.  Thus, in the simplest of all firearm systems, a burning “match” is placed in contact with a small quantity of blackpowder in a “touch-hole” which then initiates a larger amount of blackpowder in the barrel of a gun.   This system worked for hundreds of years in the cannons you see fired in all the movies.                                                                                                                                                
The gun is aimed and the application of the burning “fuse” simply initiates the blackpowder.  The energy in the arm of the man holding the fuse, and the energy in the already burning fuse is enough to initiate the stored chemical energy in the blackpowder in the barrel.                                                                                                                                                                                                                                                               
But in a small firearm there’s an issue of the man pointing the gun and initiating it at the same time. Generally these firearms were pretty large and required two hands to point at a target.  So quite often the firearm was supported with a crutch allowing the firer to point it with one hand, sight the barrel with an eye at a target and use the “spare hand” to place the burning fuse on the touch hole. 
Firing an early firearm without a trigger and serpentine
But let’s face it, that’s a bit fiddly. The touch hole is small and it might be a bit awkward. The firer is concentrating on doing two things, keeping the target in line and finding a small hole with the burning fuse in one hand.   So, with some very simple engineering the matchlock was developed.    All that happened was that a simple S shaped lever was introduced onto the body of the firearm. One end of the lever held the burning fuse in  a specific position, the centre of the “s" shaped piece of metal was a pivot joint and the bottom end of the s was pulled with one finger.  The placement of the s shaped lever (a “serpentine) ensured that the burning match always found the touchhole or the pan at the entrance to the touch hole, and the firer could use two hands to aim the firearm, concentrate on the target and just use a finger to pull the “s" shaped piece of metal.
A very early, simple matchlock arquebus
 Now , manufacturing such a firearm was pretty simple, and within the engineering skills of the average door-lock manufacturer of the 15th century which simply used levers and pivots.   So matchlock firearms were relatively easy to manufacture and relatively cheap. Matchlocks continued to be produced from the 1400s for about 250 years.  I think this is important to understand - although better technology was invented in a series, starting in the early 1500s, match-locks remained a simple and cheap firearm and so were the most common at least until well in to the 1600s.
A nice image of a Japanese matchlock mechanism showing a pan cover
Now, there are some operational weaknesses with the simple matchlocks.  In the simplest of all matchlocks the pan or the entrance to the touchhole  is permanently exposed to the elements. So in poor weather the firearm simply won’t work.  Also the glowing match gives away both the position of the firer and the nature of their weapon.   Both these weaknesses were partially addressed.  Firstly a mechanism of a sliding or levered cover to the Pan or the entrance to the touchhole was developed, requiring some more intricate engineering so when the serpentine was moved then a cover was moved out of the way allowing the match access to the pan.  A bit complex.  Some attempts, too, were made to hide the burning match in a box, but not very effectively. Burning fuse also, by the way, made the weapon unsuitable for those guarding stores of ammunition.  So in the early 1500s the wheel-lock was developed.                                                                                                                    
In large part the wheel-lock invention was enabled by advances in engineering, and specifically advances in engineering from clock making.  On a fundamental level, the wheel-lock utilises, for the first time in a firearm, “potential energy” in a spring.   A wheel-lock, consists of a steel wheel, which has a small chain wrapped around its axle. The wheel is rotated with a spanner, this wraps the chain around the axle and the other end of the chain is attached to a spring.  Thus when the wheel is rotated it induces a potential energy into the spring. The spring is then held by a trigger. A second spring is then set up to hold the serpentine. In this case the serpentine doesn't hold a burning fuse, but a small lump of iron pyrites.  The spring acting on the serpentine holds the pyrites in contact with the rim of the steel wheel which usually has grooves on its circumference and some small notches to encourage friction.  When the main spring holding the chain attached to the wheel is released by pulling the trigger, the steel wheel rotates and, because it is in contact with the iron pyrites, sparks are formed.  The sparks initiate blackpowder in the pan.
So we have the potential energy in the spring, making kinetic energy in the wheel , which initiates chemical energy in contact with the pyrites, which initiates the chemical energy in the blackpowder, which converts to kinetic energy in the projectile, and that kinetic energy is transfered t o the target t cause damage.  A nice little chain, but one which requires a significantly more detailed engineering capability than a match-lock.                                                                                                         
The wheel-lock however has several advantages.   It is safer, in that safety catches can be applied to both the serpentine and the wheel.  The presence of a firearm is not given away by the burning fuse.  It can be prepared well in advance of use (if the springs don’t deform as some where liable to)  The firearm can be concealed. Since it is possible to conceal, the firearm was then made smaller, and so the pistol appeared for the first time, able to be held about a person, and the same person could indeed carry two or three wheel lock pistols. Since this is a blog about explosive devices, then of course the wheel-lock became a potential initiator for IEDs - the device could be hidden and initiated at a point of the firers choosing, perhaps say with a string to the trigger or a potential booby trap switch. IEDs are more suited to initiation by potential energy.
But now we have economics at play. The high level of engineering and therefore cost required for a wheel-lock would make it usually unsuitable for a one-time-use in an IED, although possible.   Only the rich could afford wheel-locks.  So wheel-locks and match-locks existed side by side for decades and indeed for at least 150 years. The economics of the engineering had some other interesting implications.  Matchlocks are simple utilitarian devices usually without decoration through the 16th century. Wheel-locks however, bought by the rich became covered in ornate art, and became models of fine engineering and artistic excellence.  Here’s some images of highly decorative wheel locks.
The fact that wheel-locks were used by the rich also had an effect on the manner in which warfare was conducted.   Ordinary infantrymen could not afford wheel-locks but the aristocratic and rich cavalry could. Cavalry tactics then evolved to make benefit of the capabilities that two or three wheel locks could provide. The cavalry galloped forward to a point within range of their wheel-locks, fired, and galloped back.   The tactics of cavalry using wheel-locks then had an impact on the types of horses and armour being used by the military. The huge horses required for armour encumbered cavalry with lances were replaced with smaller, quicker more agile horses. This perhaps lead, by connection, to the evolution of horse racing and blood stock management.   The armour, designed to to defeat the weapons of the medieval horseman was discarded - armour could be produced to protect against the bullets fired from wheel-locks but frankly it was too heavy.  So the nature of warfare rapidly evolved.  One could say that the nature of warfare evolved over the period of between 1500 and 1620 entirely because of the initiation system moving to a potential energy storage device (a spring) for the initiator rather than a chemical energy storage initiator (the burning match).                                                              
Subsequent evolutions of the gun-lock technology brought together the principle of a potential energy store (from the springs in the wheel-lock), with simpler engineering requirements.   I think that the spring-held serpentine of the wheel-lock got people thinking. Firstly pyrites wasn't always a solid enough material to hold reliably in the jaws of the serpentine, and indeed the spring holding the pyrites wasn’t designed to cause the pyrites to impact with the steel wheel, just hold it against it.  I think that the metallurgy of springs improved throughout out the 16th century.  A powerful spring could cause a flint to strike a steel firmly and reliably enough to set a spark - earlier technology wouldn't allow that - the springs would break or the springs would deform very quickly. But the evolution of clocks and associated engineering developed through the 16th century so that steel suitable for using in springs evolved.  All of a sudden there was a metal available that could be used in a  spring that could force a serpentine holding a flint hard enough to cause sparks. The “snaplock” then developed in about 1540 utilised the same serpentine used in the match-lock and wheel-lock, but this time powered by a strong spring to strike a “steel” to cause sparks - subsequent developments of the snap-huance and then the flintlock were simply improvements on that design, improving its reliability and weather protection.  Essentially then in energy terms, the potential energy inherent in the spring that powered the wheel in the wheel-lock was changed to potential energy in the main-spring of the flintlock. Crucially though the engineering required of the flintlock was still considerably simpler than the technology used in the wheel-lock. Flintlocks could be pretty much mass produced while wheel-locks remained the product of a highly skilled craftsmen. As an aside, the engineering tolerances required of the wheel of the wheel-lock needed to be much tighter than the engineering tolerances in a flintlock. In a wheel-lock the wheel rotates through a slot in the “pan” and if the slot is too big then the gunpowder falls through it.   The fact that flintlocks used potential energy , but were also cheap and able to be mass produced means that they became attractive to use in “one time use” IEDs such as this device . The first mine , Samual Zimmerman's "fladdermine" also use a flintlock mechanism.                                                                                                                                              
It is clear from reading up about the history of clock development that many of the principles of engineering in clocks developed during the period of about 1550 - 1750 were subsequently applied to the production of munitions fuses. There’s probably another blog (or book!) to be written about that. 



18th Century TPU, 19th Century Grave Robbers

I've blogged before about the use of flintlocks and other gun-lock mechanisms used as initiators in IEDs between the end of the 16th century and the middle of the 19th century.   Some recent digging has made me think that the integration of a timing mechanism with a flintlock mechanism was a widely used system, perhaps not regularly within an IED but widely enough that it's use must have been well known, even if only as a potential initiation system.  Here's some images of a couple of peculiar alarm clocks which I think make the point well. The operator sets a time on the clock which when reached released a spring loaded trigger on a flintlock.  A small amount of powder is then initiated which also ignite the wick of a candle which then by a linked spiring stands up in the box. These are I think from the period 1715- 1740 or thereabouts. Nowadays we'd call these a Time and Power Unit (TPU)

 I have also found a "set gun" which attached a flintlock to a tripwire, used as a deterrent for both for both poachers and grave robbers. Here's an image of one of these.  

To be clear I'm not suggesting any of these are IEDs, just that such a mechanism could have been used at the tme to initiate explosive devices.  The set guns were outlawed eventually but in 1878 an inventor, Mr Clover of Columbus, Ohio then came up with a "coffin torpedo" to deter grave robbers who opened a coffin with something like a shotgun cartridge, initiated by the opening lid.  "Torpedo" was the name given to IEDs at that time.   

In 1881 a Mr Howell invented two "Grave Torpedos", much more like IEDs and images from the patent application is shown below. These were much more like an American Civil War land mine, placed on top of a coffin with a plate above it, designed to be initiated when the grave robbers dug down.

These were effective - a grave robber was killed by the device and an accomplice wounded: