THE DACHAU GAS CHAMBERSHarry W. Mazal OBE
Adolf Hitler became Chancellor of Germany on January 30, 1933. Foreseeing the need to legalize the incarceration of political opponents, a Presidential Order, signed by President von Hindenburg, Chancellor Adolf Hitler, Minister of the Interior Frick, and Minister of Justice Dr. Gürtner, appeared exactly one month later on February 28, 1933 in the Reichsgezetzblatt Nr. 17 (Legal Bulletin of the Reich No. 17). The Order included the following:
The Dachau Concentration Camp officially opened on Wednesday, March 22, 1933, a scant six weeks later. An article in the Münchner Neueste Nachrichten of March 21 reported:
A similar article appeared on the same date in the Völkischer Beobachter, the Nazi Party newspaper. Hitler had acquired modern American rotary presses to increase circulation of this daily with a loan from Ernst Hanfstaengl. <photo 3>
Less than three months after their ascendancy to power, the leaders of the Third Reich had eliminated or severely curtailed the basic, unalienable civil rights of the German people. It was but a portent of what was yet to come. <photo 4 >
Concentration Camp Dachau : The Early Days
By the first of May, 1933, there were 1200 inmates in the camp; mostly political prisoners from Munich. These were comprised by " members of the Social Democratic and Communist parties, many Catholics and many Jewish doctors and lawyers."  Guards began murdering inmates from the very first days of the camp's existence.
Close to the end of 1933, 4,821 registered prisoners had arrived in Dachau. By 1945, 206,206 prisoners had been registered. The total number of dead may never be known. Soviet prisoners of war were summarily executed by the thousands, civilians were assigned by the Gestapo to the camp for "Sonderbehandlung" ("Special Treatment," a Nazi euphemism which signified "killing"), and a great many died in evacuation marches and death marches. These deaths were never registered. The International Tracing Service in Arolson reports 31,591 dead among the prisoners that were registered.
Disposal of Bodies
Before the Nazi invasion of the Soviet Union in 1940, deaths were caused principally through natural attrition, exposure, disease, or as the result of executions for supposed violations of the "Disciplinary and Penal Code for the Prison Camp" issued by SS-Oberführer Eicke on October 1, 1933, which included:
The edict was nothing less than a license to kill on the merest pretext. Hans Beimler, who was imprisoned in Dachau for only four weeks in 1933 before he was able to escape reported the brutal murder of nearly 50 men during that period. 
Dead prisoners posed a considerable problem for the Nazis. Initially the dead were buried in common graves at the Leitenberg and Waldfriedhof. Records show that 6,223 bodies were exhumed from the Leitenberg, and 1,124 were taken from nine different places.  It is probably impossible to determine how many of the dead were buried there before construction of the crematories, and how many were put in common graves toward the end of the war when the ovens could no longer cope with the number of dead. <photo 5>
By 1940 the problem of body disposal had reached a critical point. Russian prisoners of war by the thousands were assigned to Dachau while an ever-growing influx of political prisoners, 'anti-socials,' and Jews, most of whom were never registered, were added to the soaring population. In 1940 alone, 22,675 new, registered prisoners were incorporated into Dachau and its subsidiary work camps. The number of unregistered deaths that occurred at the camp will probably never be known:
One such example of unregistered deaths by execution in Dachau is offered:
The first crematorium was erected in 1940, on the North-West corner of the camp, and can only be reached over a small footbridge. The ovens are housed in a wooden shed surrounded by a grove of trees. <photo 6><photo 7> The well-concealed site was carefully chosen, and further isolated from the main camp by a large drainage ditch, the camp wall, a barbed wire fence, and a large ditch with running water. <photo 8><photo 9><photo 10> It is quite impossible even today to see the old crematorium from the camp, and many visitors miss it altogether even when walking within a few yards of it on the path to the new crematorium. <map 1>
By early 1942, the death rate outstripped the capacity of the old crematorium originally built by Topf & Söhne. The manufacturer's name is quite visible on the doors of the furnaces. <photo 11> <photo 12> Plans were drawn up in April, 1942 for a more efficient four-furnace crematory which, from its early planning days, incorporated five gas chambers.  <photo 13><photo 14> <photo 15> On July 23, 1942, the order was issued from the SS Headquarters in Berlin to commence construction of the crematorium at a cost of RM150,000.  <photo 16>
The new crematorium incorporating five gas chambers four of which were designed specifically for fumigation and a fifth for homicidal purposes was completed in 1943. This new crematorium would be known by the ominous-sounding name of Baracke X.   <photo 17> <photo 18> <photo 19> <photo 20>
It must be pointed out that the ovens at Dachau or other Nazi camps are not, strictly speaking, "crematoriums." A conventional "crematorium" is designed to cremate one body at a time. This implies a heating cycle, an incineration cycle, a cooling cycle, and the recovery of ashes from the deceased. An oven that cremates bodies in a continuous manner is more aptly called an "incinerator". Cremations of cadavers, in this last case, are carried out with no cooling period or recovery of ashes between cremations. New corpses are simply fed into the ovens as the old ones are consumed. The cost of operation of an "incinerator" is considerably lower than that of a "crematorium," and the efficiency is considerably higher. With coal and other fuel often in short supply, and with a substantial increase in the number of cadavers to be incinerated, the ovens ran continuously; several bodies were often burned together and the ashes intermingled:
* Other estimates put this time as low as 10-15 minutes:
The Gas Chambers
Two issues will be now be addressed:
1) The intended purpose of the gas chambers built in Baracke X.
2) The actual use of the chambers once Baracke X had been built.
It may come as a surprise to many readers that Baracke X incorporates five gas chambers all of which were included in the original design. These were built and exist to this date. Most visitors to the Dachau Camp, drawn by horror to the main entrance of the crematorium and to the large room designated as a disguised homicidal gas chamber, rarely venture beyond these areas. The chamber (room # 8) is located next to a mortuary room, which in turn connects to the large area housing the four huge furnaces. <photo 24> <photo 25>
There are, however, four additional chambers which figure prominently in the original drawings of the new crematorium (Baracke X) . These are located on the southern side of the building and were specifically designed and constructed for fumigation or disinfestation. <photo 26> <photo 27> The overcrowding of Dachau brought serious problems to the inmates, the most dangerous of which was lice-borne typhus. These four gas chambers were specifically designed to fumigate clothing, bedding, blankets, etc., using a well-proven technique: hydrogen cyanide gas in the form of Zyklon-B pellets. These chambers were identical in design as those proposed for the same purpose at Auschwitz: <photo 28 >
The proposed disinfestation gas chambers in Auschwitz were designed to use a unique device which would open the can containing Zyklon-B, dispense the crystals or pellets onto a tray, and blow hot air on the pellets to ensure rapid evaporation.  <photo 29> The authorities at Auschwitz were apparently not able to justify the expenditure that these mechanized chambers would entail and the project was dropped.
The cost of the new crematorium at Dachau, however, included the construction of four specifically-designed gas chambers for disinfestation <see photos 14 and 27 above>, each supplied with the identical Degesch Zyklon-B dispensers that had been proposed for Auschwitz.. <photo 30> The disinfestation chambers are small, narrow, and with low ceilings. They are better suited for treating clothing, bedding material and blankets than for exterminating human beings. Once disinfestation of the material was completed, the operators would simply need to open the outer doors and let the remaining, but very volatile, gas diffuse without risk into the atmosphere. The four parallel chambers in the Dachau crematorium are unquestionably gas chambers designed specifically for exterminating lice and other insects.
A larger room adjacent to the four disinfestation chambers is also a gas chamber but this one was designed specifically for homicidal purposes. Any doubts that this chamber is a gas chamber are rapidly dispelled upon viewing the exhaust vents on the ceiling of the room <photo 31 >, the exhaust chimney on the roof <photo 32 >, and the metal doors that are identical in design to those used by the disinfestation gas chambers <photo 33 > <photo 34>. It would appear that the fake shower heads on the ceiling of the chamber <photo 35> , the sign over the door stating Brausebad (shower room) <photo 36> and the smooth brick finish simulating tiling < see photo 41 below> were part of an elaborate ploy to make the victims believe they were going to take a bath after having deposited their clothes in the passageway connecting the disinfestation chambers with the homicidal chamber.
Further evidence of its design as a homicidal chamber are the two bin-like drawers leading from the gas chamber to the exterior. <photo 37> <photo 38> <photo 39>. The only possible explanation for these bins is that they were designed to receive the granules of Zyklon-B (or some other lethal volatile poison) from a small tin. The person in charge of a homicidal gassing need only don a gas mask, open the two bins, and dump part of a small tin of Zyklon-B into each one. Having done this, the operator would close the bins, which are protected from interference from the victims by a protective grating, <photo 40> <photo 41> and wait a few minutes until all the victims were dead. At this point, the powerful mechanical extractor could be energized sending the poisonous fumes into the atmosphere, drawing fresh air through a small hatchway located above the bins. The bodies could then be moved into the mortuary chamber to await incineration in the adjoining crematory furnaces.
The question arises of the difference between the method of dispensing of Zyklon-B to the disinfestation chambers and to the extermination chamber. Quite simply: the exposure time and concentration of hydrogen cyanide gas for killing insects is considerably higher than that which is needed to kill humans. According to the manufacturers of the product, it only requires 0.3 grams per cubic meter to kill human beings, whereas concentrations of up to 10 grams per cubic meter were routinely employed to destroy insects.  The relative ease with which it is possible to kill humans with low concentrations of hydrogen cyanide makes it simpler and less expensive to use the drawer-like bins in the homicidal chamber rather than to use the costly Degesch dispensers. Additionally, the bins would allow for other volatile poisons to be employed as suggested by Rascher in his letter to Himmler. [see below]
A suspicious and heretofore unexplained structure bears mentioning. What appears to be a wooden screen blocking the area where the bin-like drawers are located on the eastern wall of the new crematorium (Baracke X) can be observed in photographs taken immediately after the camp was liberated by the Americans. <photo 42> <see also photo 17 above>. This screen seems to be about 16 feet wide and six feet deep. It does not appear to have any roof-covering. If it was indeed a screen, it would have allowed operation of the bin-like drawers by one or more perpetrators without any possibility of being observed by any casual bystanders.
Actual Use of the Gas Chambers:
It is almost certain that the fumigation or disinfestation chambers were used for their designed purpose. Bishop Neuhäusler quotes Michelet's Street of Liberty:
The official historian of Dachau, Paul Berben, further states:
Although the administrative authorities at Dachau, some famous prisoners and many historians are quick to point out that the large gas chamber at the camp was never used for homicidal purposes, there is at least some evidence to the contrary. Bishop Neuhäusler, for example, states:
There is also considerable evidence that at least 3,166 prisoners were sent to Hartheim Castle in Linz. Here they were quickly put to death in the small gas chamber originally used to destroy the mentally retarded and handicapped. 
Dr. Sigmund Rascher:
An acquaintance of Heinrich Himmler, who later fell into disfavor and was executed, Rascher was an active participant in the grotesque so-called "medical experiments" at Dachau. These included immersing prisoners in cold water until they succumbed, or evacuating a chamber to simulate high altitudes until the screaming prisoner died.  It is beyond the scope of this essay to expand on this aspect of Rascher's activities nor of his peculiar credentials. What does bear analysis is a communication written on his letterhead sent to Himmler on August 9, 1942.<photo 43> A translation into English reads:
This letter has caused considerable polemic. Having established that the large gas chamber was indeed a homicidal chamber, little other evidence, apart from Rascher's letter had surfaced to confirm its actual use on human beings. There is, however, a little-known book that might support the use of this gas chamber at least for experimental purposes.
A British Intelligence operative, Captain S. Payne Best had been kidnapped, together with other British officers, by the Gestapo from a hotel in Venlo, a small Dutch town bordering Nazi Germany. The kidnapping took place before the Germans had occupied Holland which was, until that moment, a peaceful neutral country. Capt. Best, a meticulous officer, intelligence specialist and compulsive diarist, was treated rather better than most prisoners of the Nazis, having been assigned cells in the areas reserved for distinguished prisoners. Initially held in Sachsenhausen, Capt. Best was moved to Buchenwald in August of 1944.
Among other privileged prisoners such as General von Rabenau, Pastor Bonnhöffer, General von Falkenhausen, and Dr. Josef Müller, was Dr. Sigmund Rascher whose rather luxurious cell (No. 10), adjoined the equally comfortable cell (11) holding Captain Best, who reports:
If, as Rascher states, they had " not succeeded in solving the problem " it implies that he had probably experimented with putting men to death in the Dachau gas chamber. Rascher remained in Dachau conducting "medical experiments" until early in 1944 when he was arrested, ostensibly for assisting his wife in the kidnapping of infants. With his departure from Dachau, it is likely that further experimentation with the homicidal chamber came to an end.
When the American forces were closing in on Buchenwald, Rascher, Best and the other prominent 'special' prisoners were evacuated to Dachau and housed in the privileged prisoner area known as the "bunker." Rascher was killed by a shot to the back of the head on April 26, 1945 in cell 73 of the Dachau "bunker."  Three days later the camp was liberated by the American Army. Best was released and went on to publish his memoirs.
Father Sales Hess O.S.B. also mentions the gas chambers in his book published shortly after the liberation of Dachau:
Dachau was liberated by American troops on April 29, 1945. The scenario that they encountered was Dantesque beyond description. Corpses were piled up helter-skelter in the morgue of the new crematorium <see photo 24 above> and in front of the old crematorium. <photo 44> .
Bodies were also found strewn about the camp grounds outside the huts where the prisoners were housed. <photo 45> Boxcars in a nearby railway siding were also found filled with hundreds of corpses. <photo 46> Nothing can explain such a crime.
Given the evidence that confronted them, it was not surprising that soldiers, observers, journalists and Congressional investigators should have assumed that the bodies found in the mortuary, on the floor of the gas chamber, and next to the old crematorium had been victims of the gas chamber. A report in a U.S. Army newspaper of the time reported:
It is generally accepted today that most, if not all of the dead found in these areas, perished through starvation, exposure, sickness particularly typhus mistreatment, and execution by means other than poison gas. Nonetheless, one survivor of the Dachau camp, Joel Sack, a Polish engineer, who visited the homicidal chamber soon after liberation reports:
Neither the reports by the U.S. Army, Father Hess nor Sack prove conclusively that the homicidal chamber was used to kill people. Until further evidence is discovered, historians will have to conform themselves with the knowledge that it was technically possible to have murdered human beings with poison gas in that room, and that the room, some 16x16x12ft high, was designed for the exclusive purpose of carrying out such a grim task. This circumstance does not free the perpetrators of their crimes. No matter in what manner the tens of thousands of unfortunate people in Dachau lost their lives, they were murdered as surely as if they had been placed in a gas chamber and asphyxiated with hydrogen cyanide gas. The intentional destruction of human life by whatever means is still murder. It is quite sufficient, for the moment, to demonstrate that the Nazis intended to use a homicidal gas chamber in Dachau, and that they designed, built and equipped such a chamber in the Dachau Concentration Camp.
 Distel, Barbara and Jakusch, Ruth, Editors, Concentration Camp Dachau: 1933 - 1945, c. 1978, Comité International de Dachau, Brussels, Lipp GmbH (Munich) ISBN 3-87490528-4, page 37.
 Reichsgezetzblatt Nr. 17, March 21, 1933
 Trial of the Major War Criminals before the International Military Tribunal, 1947, United States Government Printing Office, Document Number 778-PS, Exhibit Number USA-247.
 Münchner Neueste Nachrichten, March 21, 1933 (clipping)
 Hanfstaengl, Ernst, Hitler: The Missing Years, c. 1957, Eyre & Spottiswoode (London), page 53
 Völkischer Beobachter, March 21, 1933 (clipping)
 Rost, Nico, Concentration Camp Dachau, third edition, translated into English by Captain Bernard R. Hanauer (no date) Comité International de Dachau, Brussels, page 4.
 Distel, Barbara and Jakusch, Ruth, Editors, opus cit., pages 212-213
 Distel, Barbara and Jakusch, Ruth, Editors, opus cit., page 73
 Beimler, Hans, The Nazi Murder Camp of Dachau: Four Weeks in the Hands of Hitler's Hell-Hounds, Modern Books, Ltd. (London)
 Berben, Paul, Dachau 1933-45: The Official History, , translated into English by Captain Bernard R. Hanauer, c. 1968, 1975, Comité International de Dachau, ISBN 0-85211-009, page 200. (See also photograph of exhumation between pages 192 and 193)
 Neuhäusler, Dr. Johannes, Auxiliary Bishop of Munich, What was it like in the Concentration Camp at Dachau?, 14th Edition, (no date), Trustees for the Monument of Atonement in the Concentration Camp at Dachau, (München), (a) page 4.
 Neuhäusler, Dr. Johannes, Auxiliary Bishop of Munich, opus cit. page 30.
 Distel, Barbara and Jakusch, Ruth, Editors, opus cit., pages 170 and 171.
 Distel, Barbara and Jakusch, Ruth, Editors, opus cit., page 172.
 Berben, Paul, opus cit., pages 8 and 176.
 Trials of War Criminals before the Nuernberg Military Tribunals, Vol. 5, "The Pohl Case", Translation of Secret Documents NO-3863 and NO-3680, Superintendent of Documents, U.S. Government Printing Office (Washington D.C.) pages 615-616
 Berben, Paul, opus cit., page 7
 Rost, Nico, opus cit. page 28
 Dwork, Debórah and van Pelt, Robert Jan, Auschwitz: 1270 to the Present, c. 1996, W.W. Norton & Co., Inc. (New York), ISBN 0-393-03933-1, page 220.
 Dwork, Debórah and van Pelt, Robert Jan, opus cit. Page 222
 Pressac, Jean Claude, Auschwitz: Technique and Operation of the Gas Chambers, c. 1989, The Beate Klarsfeld Foundation (New York), page 18
 Neuhäusler, Dr. Johannes, Auxiliary Bishop of Munich, opus cit., page 16.
 Berben, Paul, opus cit., pages 8-9
 Neuhäusler, Dr. Johannes, Auxiliary Bishop of Munich, opus cit., page 15.
 Berben, Paul, opus cit., page 240 (Appendix 19).
 Berben, Paul, opus cit., pages 123-137
 Bundesarchiv Koblenz
 Best, Captain S. Payne, The Venlo Incident, c. 1950, Hutchison & Co., (Publishers), Ltd. (London), page 186. [A curious note regarding Raschers death appears in a footnote on page 203 of Nazi Mass Murder edited by Eugen Kogon: "Dr. Rascher and his wife (also condemned to death) has tried to pass off as biologically their own two children they had merely taken into their home. That this could be made an offense punishable by death is yet another incredible aspect of the Nazi regime.]
 Benz, Wolfgang, "Sigmund Rascher, M.D.: A Career", pp. 22/45 Dachau Review 2: History of Nazi Concentration Camps Studies, Volume 2, 1990, Edited by Wofgang Benz and Barbara Distel, Comité International de Dachau (Brussels), page 45.
 Hess, P. Sales O.S.B. Dachau: eine Welt ohne Gott, c. 1946, Sebaldus-Verlag, Nürnberg, pages 170-171 (Translation from the German by Harry W. Mazal)
 United States Army, Stars and Stripes, May 3, 1945
 Sack, Joel, Dawn After Dachau, c. 1990, Shengold Publishers, Inc. (New York), c. 1990, ISBN 0-88400-141-5, pages 44-45
<photo 1> Reichsgezetzblatt Nr. 17 (Legal Bulletin of the Reich No. 17), February 28, 1933
<photo 2> Münchner Neueste Nachrichten (The Munich Latest News), March 21, 1933
<photo 3> Völkischer Beobachter (The People's Observer), March 21, 1933
<photo 4> View of the Dachau Memorial. (photo by the author)
<photo 5> Disinterment of victims at the Leitenberg cemetery. Berben, Paul, opus cit. page 128
<photo 6> Footbridge between camp and the crematoriums. A grove of trees, to the left of the woman with the long coat conceals the old crematorium. (photo by the author)
<photo 7> View of the wooden shed containing the old crematory ovens. (photo by Dr. Daniel Keren)
<photo 8> Drainage ditch, barbed wire fence and concrete wall separating the camp from the crematoriums and gas chambers. A guard tower is in the foreground. (photo by the author)
<photo 9> Drainage ditch, barbed wire fence and concrete wall separating the camp from the crematoriums viewed from south to north. Contemporary photo circa 1939. Hess, P. Sales O.S.B., Dachau: Eine Welt Ohne Gott, c. 1945, Sebaldus Verlag, Nürnberg, following page 80.
<photo 10> Water channel running behind the camp wall, parallel to the drainage ditch. (photo by the author)
<photo 11> Topf name visible on oven door casting. (photo by Dr. Daniel Keren)
<photo 12> Well-used ovens in the old crematorium. (photo by Dr. Daniel Keren)
<photo 13> Location plat of new crematorium, 23 May, 1942, Dachau Archiv.
<photo 14> Architectural layout plan of new crematorium, 23 May, 1942. Note the four disinfestation chambers at left. Staatsarchiv, Nürnberg.
<photo 15> Front and rear renditions of new crematorium. Note exhaust chimney above homicidal chamber to the left of main crematory oven stack. Staatsarchiv, Nürnberg. (Notations in English by the author)
<photo 16>Letter dated July 23, 1942 from SS-Sturmbannführer Lenzer to the Dachau camp administrator authorizing construction of new crematorium. Staatsarchiv, Nürnberg.
<photo 17> Photograph of crematorium taken after liberation in 1945. Note wooden structure in front of homicidal chamber shielding bins. U.S. Army photograph.
<photo 18> Photograph of new crematorium taken from the grove of trees. <photo by author>
<photo 19> New crematorium, view from north to south. <photo by author>
<photo 20> Entrance doors to crematorium. <photo by author>
<photo 21> Crematorium ovens 2, 3, and 4. <photo by author>
<photo 22> Crematorium oven 1. <photo by author>
<photo 23> Ash recovery hatches on the side of oven 2. <photo by author>
<photo 24> Mortuary adjoining crematorium as found by liberating American forces in 1945. Staatsarchiv, Nürnberg.
<photo 25> Multi-language sign outside of Dachau homicidal chamber. <photo by author>
<photo 26> Multi-language sign outside of Dachau fumigation chambers. <photo by author>
<photo 27> Two of the four Dachau fumigation chambers. <photo by author>
<photo 28> Engineering drawing with proposed fumigating chambers for the Auschwitz concentration camp. Dwork, Debórah and van Pelt, Robert Jan, opus. cit. page 220. (Notations in English by author)
<photo 29> Zyklon-B dispensing device as proposed for the Auschwitz fumigating chambers. Dwork, Debórah and van Pelt, Robert Jan, opus. cit. Page 221.
<photo 30> Zyklon-B dispensing device as installed in the new Dachau crematorium. . <photo by theauthor>
<photo 31> Ceiling of homicidal gas chamber in the Dachau crematorium. Note exhaust grille and fake shower heads. (photo by Dr. Daniel Keren)
<photo 32> Exterior view of homicidal chamber. Note exhaust chimney directly overhead. (photo by Dr. Daniel Keren)
<photo 33> Door of homicidal chamber leading into mortuary. (photo by Dr. Daniel Keren)
<photo 34> Door of homicidal chamber as found by the American liberating troops in 1945. ( U. S. Army photo>
<photo 35> Close-up of fake shower head. (photo by Dr. Daniel Keren)
<photo 36> Door into homicidal gas chamber from the undressing area. Note sign identifying it as a Brausbad (shower bath). <photo by author>
<photo 37> Outside view of homicidal gas chamber showing the two bin-like drawers designed to introduce lethal poisons. (photo by Dr. Daniel Keren)
<photo 38> Medium view of exterior of homicidal gas chamber showing one of two bin-like drawers and closed ventilating inlet. (photo by Dr. Daniel Keren)
<photo 39> Close-up view of bin-like drawer designed to introduce lethal poisons into the homicidal chamber. Note hinges on bottom allowing the device to rock in or out. (photo by Dr. Daniel Keren)
<photo 40> Close-up view of interior of bin-like drawer showing protection grating. (photo by Dr. Daniel Keren)
<photo 41> Close-up view of grating and bin-like drawer from within the homicidal gas chamber. (photo by Dr. Daniel Keren)
<photo 42 > Bodies piled up in front of the wooden screen located in front of the bin-like drawers. (photo appearing on page 464 of: Lenz, Johannes Maria, Christus in Dachau oder Christus der Sieger, c. 1957, Buchversand: Libri Catholici).
<photo 43> Letter from Rascher to Himmler, August 9, 1942. Personal Records, Berlin Document Center.
<photo 44> Bodies piled up outside of the old crematorium when Dachau was liberated. Berben, Paul, opus cit., photo between pages 192 and 193 by J. Brichaux, a Belgian prisoner.
<photo 45> Bodies lined up outside the huts (US Army Photograph)
<photo 46> Bodies discovered in railway cars by American troops. (Imperial War Museum, London)