StandingWellBack

You can contact me at rogercdavies(atsquiggle)me.com  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.

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Monday
Aug062018

Explosive Drones in public

The case very recently of the apparent explosive drone attack in Venezuela highlighted something to me which I think is significant about the use of drones in terrorist attacks.  It's not just the technology which offers a new challenge, but there’s another aspect which is interesting or even disturbing related to the psychology of terrorism.
 
Drones have been used in Iraq and Syria with explosive payloads for a few years now, and I wrote about these a couple of years ago. But this attack in a highly public non "war" venue highlights something new, and something worthy of some thought.  
 
Most terrorist attacks occur with the actual end result being the first the victim and bystanders become aware of it.  Attacks using most weapons give no tactical warning:
  •     You can't see a bullet fly, you only see its final effect
  •     You can't see a mortar round or an artillery round fired towards you.
  •     You don't see the booby trap before it explodes because it is hidden
  •     You don’t see the roadside bomb before it explodes by command because it is hidden
All these limit the response to a specific attack to post-attack responses.  It makes the attack somewhat impersonal. Victims accept that they are/were victims in part becuase of surprise. While the attack may be fearful, after the attack occurs it is more about developing actions that respond to its occurrence.
 
There are a more limited range of attacks that victims and bystanders have immediate warning of and indeed these have become favoured of late - the rampaging terrorist with a weapon (knives or firearms) or the terrorist using a vehicle (either as a suicide bomb or simply to mow down people in the street.) These attacks sometimes give a few seconds of warning. People can run, they can hide, take cover or in some cases fight back. But they are in their nature more “terrifying” perhaps psychologically because you can see them happening potentially before the denoument. They feel much more personal.
 
But maybe drone attacks are different again. If we take the supposed Venezuela attack at face value (and there is still confusion over the actual incident), it appears that one or more explosively-laden drones flew over a crowd towards a target before exploding.   The delivery mechanism was seen before the explosion(s). The targets and bystanders essentially had a few seconds warning that there was something fearful happening and yet unlike the rampaging terrrorist or the vehicle attack, in this case the added third dimension of an aerial attack applies a third dimension, limiting, perhaps the “flee” response and maybe the hide response too. So a much greater degree of helplessness occurs.   And the nature of drones then makes them extremely difficult to “fight”.  If you have say four or five seconds to respond to an incoming drone with a firearm, well that ain’t gonna work. By the time you have your rifle off your shoulder, and ready to fire it is too fast, and too difficult a target. Plus you have the crowds and public in a built up area - so firearm response is pragmatically a non-starter in most circumstances like the Venezuela attack. There are some directional shoulder “fired” EW weapons, but would you want the drone to crash into the crowd carrying its explosive payload, even if you had the time? The same might apply to some other electronic defensive measures. 
 
Take a look at this link below, supposedly one of a number of drones which exploded in Caracas. Imagine those flying down a street in your city centre and the responses that you as a cop might take. Imagine the perspective of the crowd seeing that happen. 
 
Looking at that video, is there something "extra" terrifying about an apparent robotic threat, of flying bombs, able to seek, to follow and to be guided at that pace to a target?  It's very "science fiction" in its novelty. Most people agree that drones will become ubiquitous in coming years, but the demonstrable proof here that they are so weaponisable raises all sorts of interesting questions about public perceptions and threat management driven by the psychological impact they can make. 
 
Thus the drone attack in these circumstances, with the public present, offers new and different challenges for the public and responders. It's a very different threat than the drone threat in war theatres.  Drone attacks such as seen in Venezuela pose the similar psychological impacts as the rampaging terrorist or the terrorist driving a vehicle - but without the terrorist having to put himself at risk. And it's three-dimensional so two-dimensional security measures such as barriers are negated to a significant degree. How we deal with explosive drone threats in public is the challenge posed. There are solutions but those developing responses need to think things through, and as I hope I have highlighted there are significant crowd management issues that need to happen in parallel.

 

Thursday
May312018

An innovative buried IED detection technology from 1400

I'm slowly researching a number of old military technology books (if I can describe them as that) written several hundred years ago. Every so often I come across something intruiging. Here's today's.

Conrad Kyeser lived between 1366 and about 1405. He was born in Eichstadt in Southern Germany but lived for a time in Prague. I have referenced his book "Bellifortis" in my last post. The book was written in (poor) Latin and contained many illustrations. Kyeser clearly copied a number of other military technology books, but there was also new material. It exists today with several versions. Some of the technology discussed is remarkable for the time of writing - paddle powered boats able to move against a current, diving suits with some form of stored air for breathing, and a variety of explosive devices, rockets and multi-barrelled revolving firearm systems.  The rocket discussion includes remarks on the need for a combustion chamber (described as a "seele" or hollow in the propellant), and that the rocket cylinder/case must be gas-tight. 

But here's something very interesting - a buried IED detection technology. Kyeser describes burning a resin to create a volume of dense thick smoke, contained under an inverted tub. Once a dense cloud is formed the tub is lifted off and the dense smoke allowed to spread across the ground of an area where a buried explosive device is suspected. Kyeser claims that if the smoke rises at any point, that is an indicator of disturbed earth, and the potential that an explosive device has been buried there. 

Now that's an interesting idea, but on the face of it, I don't have any particular belief that it might work.  If a heavy gas rises it perhaps could be due to convection, but why would disturbed earth have convection , I assume associated with a thermal energy release from distrurbed ground?  I can imagine certain theoretical scenarios where a dark soil is exposed as the device is buried and that causes slightly more solar energy to be absorbed, and then released, but that's perhaps stretching it a bit. Maybe a buried barrel of gunpowder previously stored in a building would retain its heat long enough when compared to the cold earth in which it was buried and that could cause some convection for a short time.  I wonder how long....

I welcome any readers who might have a better explanation, email me at the email address explained above right.

Wednesday
May022018

The history of metal-cased military rockets - an investigation

A couple of years ago a wrote a few posts about the emergence of metal cased military rockets as a weapon system in the early 1800s. In retrospect I made some hurried assessments, and after a while digging I’d like to revisit. The links to my older posts are below but I’ll repeat some of the story here for coherence. This is a story of terrorism, weapons technical intelligence, politics, subterfuge, tall tales and obfuscation, leading to financial success for one individual (William Congreve) that perhaps wasn't entirely deserved.  The traditional, commonly accepted wisdom was that Congreve “invented” rockets in about 1804, introducing “new” metal-bodied rockets, and also introducing larger calibre and longer range variants. He was supposedly "inspired” by the use rockets by Tipu Sultan in the Mysorean wars in India in the late 1700s.  I think that is a misrepresentation (mostly by Congreve himself), of a much more interesting story which I’ll try to make here.  I’ll also try to give credit for what I think Congreve deserved . I have been encouraged by a new colleague, a keen historian from India, Nidhin Olikara from Karnataka in India. Nidhin is involved in some exciting research in this area which I cannot reveal yet. Mr Olikara’s blog is here:  

 

I’ll lay the story out chronologically as best I can:
  1. After being “invented" in China, rockets appeared first in Europe in the late 1300s and early 1400s. Rocketry was discussed in the book “Bellefortis” written in about 1405. However I think there is a red herring - the picture below, from Bellefortis, is quoted often as an image of a rocket. But I think it is not - to me it is simply a spear head, and the “rocket vent” is simply the socket for a spear. Some people quote the size of the man holding the rocket/spear but the other images within Bellefortis are massively inconsistent in scale too.  I do accept however that Bellefortis does apparently discuss rockets elsewhere in text.

Rocket or spearhead with socket? I think the latter.

2. Throughout the 1500s and 1600s rockets were well known in Europe, mainly as a component of massively complex fireworks displays which became very popular in the late 1500s onwards. Leonardo da Vinci discussed rockets and a number of books about “pyrotechnics" were published. Some of the books clearly made the jump from rockets as a form of pyrotechnic entertainment, to rockets as a military weapon.  In the 1500s rockets were clearly being developed by Conrad Haas (1529 -1569) in Austria/Hungary. Haas’s technology was surprisingly advanced, and included bell shaped nozzles and multi-stage systems.

Note the venturis on the rockets and the engineer creating a combustion chamber with a spike  

3. Haas probably influenced a German, Johann Schmidlap who developed further the staged rockets in about 1561.

Double and triple stage rocket motors4.  In the late 1500s and early 1600s there were a number of experts publishing instructions on rocketry, these include the aforementioned Haas and Schmidlap, and others referred to by later authors as “Brechteltus”, Diagus Ulfanus, Adrian Roman, James Valhouse, Furtenbach and Frontsbergue. Many of thse authors/experts developed their own formulae for the best dimensions of rockets in terms of diameter and length. Many also describe a very specific number of taps with a mallet of a specific weight for driving a needle into the packed rocket for the purposes of optimisng the rocket motor ignition surface/chamber. This may seem an obscure instruction but is important.  As far as I can tell these rockets were not metal cased but made from paper or card.   In these early years of rocketry I understand that the propellant was standard blackpowder (gunpowder). As firearms developed over this period improvements were made to gunpowder to speed up its reaction.  This made it rather too powerful for rockets with the pressure from the product gases being very high and the cardboard and paste cylinders could not contain the pressure so the tube ruptured.  So rocket gunpowder was made by adding additional carbon (charcoal) which reduced its burn rate.  This issue is fundamental to the development of rockets over the period - having a slow enough burn rate to not rupture the body of the rocket, but enough to project the rocket forward. Much trial and error went in to the development of effective geometry and hence design and production of the rocket motors.  I have found some vague references to the military use of rockets against cavalry in 1600 but so far I have no detail.

 

 

5.  A book was written by Jean Appier in about 1620, called La Pyrotechnie de Hanzelet Lorrain.  Here’s an image of a simple rocket design from that book. Note the “warhead” with a fuse that is initiated as the rocket motor finally competes burning. Still there is no sign as yet of metal cased rockets. Note the combustion surface in the rear, created by tapping a mallet into the packed propellant.

Note warhead initiation when motor finishes burn

6.  In 1635, and English book called Pyrotechnica by Robert Babington detailed rocket manufacture. These were not metal cased. Here’s a diagram of the mould used to create the rocket motor. Note the “needle” used to create the correct combustion geometry within the rocket’s gunpowder. Many of the documents and books discussed here recount how the needle is inserted into the packed gunpowder and gently knocked into place with a number of blows from a hammer. Basically the mould former on the left is lined with paper and card, filled with damp gunpowder, then the needle inserted and tapped into place and then dried. The needle is removed and the vent/nozzle formed (“choked”) with a twist of card held in place with string. This rocket is two and a half inches in diameter (which is a dimension that will be repeated in the future. Babington’s book is remarkably detailed. Babbington describes that the best paper to use for the body (“coffin”) of the rocket should be “old law books”!  He then describes a range of explosive compositions and how to make them. The thrust of Babington’s book is entertaining firework displays - but it is fascinating how some of his more exotic pieces presage the use of sub-munitions. He also describes a range of test apparatus to allow the testing of gunpowder.

 

Rocket mold, cross section and needle for making combustion chamber.

 

7.  Another book  “The Great Art of Artillery" by Kazimierz Siemienowicz published in 1650 also described a number of rocket systems.  Again I can see no detail referencing metal cased rockets but there is considerable discussion about the variants of propellant mixes needed for various sizes of rockets.   This document provides extremely detailed manufacturing instructions.  (I am using an English translation published in 1729.)  it is interesting to note that Siemienowicz comments about the habit of “pyrobolists” (those making rockets) to keep the methods of manufacturing very secret - but who let the secret out while drunk…  Siemienowics describes rocket cases made from paper, pasteboard in some cases reinfoces with wound thread and in some cases made from wood, with conical noses.  The paper ones are described in some cases as being reinforced with iron wire, “for fear the powder would split it".  He does describe however a range of quite large rockets.  Here’s a diagram of some of a range of Siemienowicz’s rockets.  Note the Multiple rocket using 7 smaller rockets (unlike Elon Musk’s 9). Note also the range of payloads and multi staging. Siemienowcz is extremely detailed on various aspects of quality control.

Siemienowicz's advanced designs

Siemienowicz appears to be an admirable chemist, physicist and engineer. He spends pages decrying his predecessors who were closer to alchemists, who described their rocket making art in mystical forms hiding the secrets of their craft through pseudo-science. Siemienowicz developed some rules for rocket making and explains the science behind these rules:
 
    First Rule: The larger the rocket the weaker and slower should the rocket propellant be (and vice versa, the smaller the rocket the faster birning propellant is required. This, he explains relates to the available surface area of the combusting propelllant’s hollow cone.
The second and third rules relate to the compostion of the propellant in certain circumstances, adjusting the carbon, sulphur and saltpetre comparative quantities.
 
Siemienowicz describes rockets that are stabilised in flight with sticks and others stabilised by fins. He also describes a stabilisation method I have not come across before using a lead ball fastened to a piece of wire that trails to the rear of the rocket, which he says acts like a stick. Another technique he describes is to add lead filings at various points in the rocket motor - very sophisticated in concept, altering the movement of centres of gravity and thrust in a complex manner.
 
8. In 1696 Robert Anderson, and Englishman wrote a book with a clear rocket design, two and a half inches in diameter and about 18 inches long.  In my earlier blogs I had misinterpreted some of the instructions from this book, assuming them to describe a metal cased rocket. After careful research and examination of this book I now no longer believe this to be the case, and my earlier assessment was an error.  I think Anderson was using paper and pasteboard and not a metal cased body.
 
9.   In the late 1700s , in the Mysorean wars in India with the British, the Army of Tipu Sultan used rockets extensively. Some of these were metal cased rockets (I think the first) and some of these rockets were recovered to England for analyis, at Woolwich Arsenal laboratory.   The laboratory was under the control of William Congreve’s father. At the time William Congreve (junior) was not employed at Woolwich, he was busy as a publisher of a political magazine. So there were military metal-cased rockets in Woolwich some 20 years or so before Congreve is credited with their invention. I believe two of these metal cased Mysorean rockets are in a museum in the UK and I’ll be checking on this in coming weeks.  My Indian friend Nidhin is investigating his excellent sources in India. I suspect that the crucial key here is the advanced metalsmithing available in Mysore at the time - often underestimated by Western historians - able to create a closed end lightweight metal cylinder, strong enough to contain the pressures of a rocket motor but light enough to not interfere significantly with flight.
  
10.  In 1803 Robert Emmet’s uprising in Dublin used metal cased rockets (two and a half inches in diameter) against British forces, it is possible using the specific design and dimensions of Anderson's rockets from 1696, or even Babbington's from 1645. However rather than use paper or pasteboard, Emmet used a metal cased rocket.  I’m not sure yet where this idea came from but it is possible it came from Robert Fulton, the American inventor whom he met in Paris in 1802. There is also a French connection to Mysore, and the French could also have recovered metal cased rockets from Mysore to Paris, and hence to Emmet.  Certainly, reports suggest that Emmet came back from Paris with specific instructions on on how to construct rockets.   Another possibility is that one of his workmen, Johnstone, had previously worked in India for the East India Company and had encountered the earlier metal cased rockets.  There is a possibility that Emmet was using manufacturing instruction from one of a number of pyrotechnic books - many had similar instructions and statements suggest those intrstuctions included tapping the rockets with needles to create combustion chambers.  I believe some of Emmet's rockets were recovered to the Ordnance laboratory at Woolwich, still under the control of Congreve’s father, in 1803.  Again, this is just a few months before Congreve junior became employed by his father at Woolwich. So we know that there had been two sources of metal-cased rockets in Woolwich laboratory before William Congreve (Junior) even began his employment there, and it is very likely tyhat Weapons technical intelligence activities and exploitation were undertaken by the laboratory..    There is also a very strong suggestion that one of Robert Emmet’s men, Pat Finerty, who had been employed by Emmet to make rockets for the Irish uprising was now taking the Kings shilling and was working in the laboratory at Woolwich, perhaps prpoviding insight and experience. Perhaps he was a British spy in the first place.
 
11.  In 1804, Congreve junior was struggling. His political publishing venture had gone bust and he needed work. But his father was a senior admninstrator for Woolwich Arsenal,  and all of a sudden he had employment at Woolwich, and he also had potential access to political patronage - vitally important for raising money.   The next few years saw Congreve develop and deploy military rockets. As a former editor of a political publication, Congreve knew the power of media and in parallel campaigned vigorously for funding and patronage to further develop military rockets. He even got himself awarded a commission as a Colonel and took charge of the rocket attack on Copenhagen and elsewhere, distrusting the military to deploy "his" invention. (In return they distrusted him and his lack of military experience).  The development of Congreve’s rockets needs a whole different blog post (or book). But the point I am making here is this:
a. Congreve was a canny political operator, seeking patronage and funding.
b. Within the politics of the time, he understood that he would optimise his chances of patronage if he could take the entire credit for the development of militarily useful rockets.
c.  Diluting the credit for the development with tales of Haider Ali or Tipu Sultan did not fit the politics of the time.
d. Nor indeed would giving the credit in any way to Irish rebels.

 

I also note that Congreve was an ardent patent producer - except when it came to rockets. was he concerned he might have been challenged?

 

So, Congreve has gone down in history as the “inventor” of military metal-cased rockets. but we can see that this was incorrect.  We can also see that a wide variety of rocketry principles were developed by scientists and engineers in the two or three hundred years before 1804.  What Congreve did do was this:
 
    a. Management of a secret technical intelligence exploitation operation which reverse engineered both the Mysorean rockets and rockets from the Irish uprising.
    b. Modern quality control and the development of robust and repeatable industrial processes- therefore enabling predictability of range etc.
    c. The development of larger rockets with greater ranges and payloads, utilisng the scientific knowledge of propellent technology at Woolwich.
    d. The development (albeit by trial and error) of improved deployment and use operationally to improve effectiveness.
 
Congreve made much of the fact that an enemy capturing a Congreve rocket couldn't reverse engineer it, and my assessment  is that this could only be because of the chemistry of the propellant, which by the technology of the day could have been tested but not analysed chemically very well. I think the techncial knowledge of the Woolwich Laboratory with regard to propellant science was crucial to the development of Congreve's rockets.   
 
In the future I hope that the work of Nidhin Olikara and his colleagues will shed more light on Mysorean rocket technology, and the pre-eminent role they had in the development of metal cased rockets, well before 1804.

 

 

Monday
Apr302018

IEDs in Belfast - 1922

Ian Jones has passed me details of IEDs in Ulster in 1922. Ian is a real EOD history guru and I recommend his excellent books

In 1922 Ireland was still being fought over and Irish republican bomb attacks were still relatively frequent (see my earlier posts such as this

Belfast was no different and a range of IEDs were encountered. There are details below of some interesting devices.  But note that the military response to these was by the Royal Engineers, not the RAOC who later became responsible in the province for such activity.  In a report published in the Royal Engineer Journal, which I cannot reproduce here for copyright reasons,  Captain EW T Graham-Carter reports a series of incidents that his Unit responded to. 

1. An attempted bombing of a telephone junction box in Arthur Square in the centre of Belfast, two IRA men disguised and equipped as telephone repair men opened a manhole cover and left a times device behind. A Sapper Unit was requested to deal with the device. The manhole was filled with water by the Fire Brigade (!) and after three hours the package was removed. The device, wrapped in sacking, consisted of a wooden box with a slider switch on the outside. The timing device was an adapted alarm clock. (There are pictures in the journal). The device failed because the alarm clock had not been wound up. The main charge was an unidentifed home made explosive or incendiary material (possibly sodium chlorate and sulphur). The initiators were interesting - two glass tubes sealed with insulating tape with two copper electrodes immersed in magnesium flash powder. Subsequent experiments were able to cause the main charge mix to explode. 

2. A series of other devcies are interesting because like many modern devices in the Middle East they utilised artillery shells, in this case 18pdr, but filled with home-made explosive. These were left in a number of "picture-houses" (cinemas), but on a number of occasions failed to function and were recovered by the Royal Engineers.

3. Other devices were designed to be hidden by or in roads. One found near Armagh consisted of hollow concrete blocks, 9in X 9in X 9in, with the addition of scrap metal as improvised shrapnel. It held 5lbs of explsoive and was initiated electrically by a command wire of 300 yards in length. 

Plus ca change, plus c'est la meme chose. Apart from the Sappers that is. 

Tuesday
Apr032018

Discovering London's bomb disposal facility from 1894

I have written before about the early British  EOD facility on Duck Island, a short distance from Downing Street, at the bottom end of St James’s Park, London. There, barely 100m from 10 Downing St is a small Island at the end of the lake, with a link to the road over a bridge.  The facility was established by Colonel Majendie and his assistant Dr DuPre in about 1894.  Col Majendie, had been working for the Home Office as Chief Inspector of Explosives for over 20 years by then having been first appointed in 1871.  During that time he had dealt with a wide variety of IEDs and associated investigations, and developed some C-IED procedures.  But the world was changing.  Following a visit to Paris that I discussed here and here,  he pushed hard for some similar facilities to the four French EOD facilities dotted around Paris at stratgic locations. The context at the time was an upsurge in anarchist bombings around the world. The 1890s were later described as “the decade of the bomb”. Majendie had undertaken overseas liaisons before, includng with the US authorities during the Fenian campaigns of the 1880s (many of the IEDs were made in the US and shipped to the UK, with US based support).  Majendie reviewed the French EOD techniques and liked what he saw. 
 
Majendie recommended three such facilities be established in London, one on Duck Island to be adjacent to the seat of government, one in “The Gravel Pit” in Hyde Park, adjacent to the district of Oxford St and Mayfair, and one in the moat at the Tower of London, covering the banking district of the city.  Duck Island was the first and I believe that the Hyde Park facility may have existed as well, but I can find no evidence or suggestion that the Tower of London site was ever set up.  The facilities were housed in wooden sheds, (like in Paris) I believe with some form of earth mound in the manner of the French facilities. I understand that amongst the equipment  in Duck Island was a hydraulic press and a mercury bath contraption for lowering an IED into a mercury bath, dissolving the solder which held together some spherical-shelled anarchist devices.  Other devices were dealt with at Woolwich Arsenal Laboratories in some circumstances in a proofing lab there, which also had a blast proof cell. 
 
The EOD facility at Duck Island (that’s my description, not Majendie’s) was operational from November 1894 and was still apparently in use in at least 1914 when some suffragette devices were taken there. IEDs were moved to the facility in the hand cart I described here or later in a specialist vehicle provided by the Army. I don't know when it fell into disuse.  However in the 1980s the derelict wooden shacks were still there, hidden amongst rhododendron bushes and out of site, out of mind.
 
 
At this stage, for reasons that are unclear the Army was tasked with removing the facility, and that task fell to the Royal Engineers. A recce of the site was undertaken, and the remnants of the facilty (fundamentally a rotting wooden shed and its contents) was taken to Chatham and subsequently and regrettably lost or scrapped.  However in the last few days I have been given sight of some photos taken by the Royal Engineers on the recce, now held by the RE Museum .  Regrettably the Royal Engineer’s Museum own the photos and have not given me permission to republish them without a not insignificant licence fee. This website simply doesn't have the budget for the license fee requested, so all I can say is that the photos appear to show what I believe is a hydraulic press, probably installed by Majendie in 1894. The photos are not too clear but the press appears to be somewhat more complex than the French version that I showed an image at the earlier link.  There appear to be a number of levers which may have been able to be adjusted remotely by attaching lines.  My assessment is that both the French and the British presses were used to “crack open” devices semi-remotely.  By this I mean set up with a specific action prepared, then activated from a distance by means of a rope or line on a lever, activating the press.  A typical anarchist device was contained in two halves of a metal sphere, soldered together.  It may be that a variety of other IED containers, such as tins and boxes could have been opened remotely by this method.  The lightweight wooden huts were cheap and easily repairable and the earth mounds would have been designed to stop shrapnel. 
 
Without more detail, which I'm investigating, I cannot tell more, and I hope to persuade the RE Museum archive to allow me to reproduce the photos without the current expense they ask for.
 
The use of a hydraulic press is interesting. Majendie would have been very familiar with such presses, his role as Inspector of Explosives meant he investigated industrial explosive accidents and he developed much of the legal regulations surrounding explosives manufacture. Presses were used extensively in the explosive industry to press explosives into shape in gunpowder mills. Presses were also used for some explosive testing. As a former Superintendent of the Woolwich explosive laboratory, Majendie would have been familiar with their use. 
 
By their nature presses are pretty resilient pieces of equipment  - take a look at the hydraulic press channel on YouTube for a feel of what they are capable of. 
 
Some key points :
  1. The facility then was a copy of the French facility, to some degree, and the French EOD/C-IED methodology appears to have been utilised (with variantions) by Majendie and Dr DuPre from 1894.  
  2. The site was operational for at least 20 years.
  3. The British and French were not the only EOD operators active in the 1890s in C-IED. See details of New York’s Owen Eagen here http://www.standingwellback.com/home/2012/1/14/the-eod-operator-who-dealt-with-more-ieds-than-anyone-else.html
  4. The facility remained derelict until the 1980s or 1990s but was then demolished and scrapped. The organisation sent to deal with it probably had no clue as to its historical importance.