Nuclear Proving Grounds and stick charts

After WW2 the USA needed to develop and test its nuclear technology. It set up two proving grounds.

Nevada Proving Ground

The Nevada Proving Ground was only 65 miles from Las Vegas and gamblers could watch the mushroom clouds from the casinos and hotels. Most of the 928 tests were under ground but 100, including the notorious ‘Dirty Harry;’ test, were atmospheric. and winds  carried the fallout of these  to the west. The town of St. George was particularly badly affected and there were  increases in  leukaemia, lymphoma, thyroid cancer, breast cancer, melanoma, bone cancer, brain tumours, and gastrointestinal tract cancers. Over 200,00 cases of thyroid cancer were believed to have been caused [see this post].  Nuclear Test Participation certificates were issued to the people who took part in testing [see post]

Pacific Proving Ground

Only low yield weapons were tested in Nevada. Most of the big bangs took place in the Pacific Proving Ground [1946-62], on the Enewetok and Bikini Atolls in the Marshall Islands. A few of the later tests were conducted on Christmas Island and Johnston Atoll.


A total of 105 atmospheric and underwater tests were conducted in the Marshall Islands. This was only 14% of the total number of tests but accounted for 80% of the megatonage, The estimated total yield of the Marshall Islands tests was about 210 megatons, including the 15 Mt Castle Bravo shot on Bikini in 1954. The Castle Bravo bomb got out of control and produced over twice the expected yield, spreading radioactive contamination over several of the Marshall Islands atolls and a large area of the Pacific.


The Marshall Islands navigators prepared stick charts’ to help them navigate between the 29 atolls and 5 islands that are spread over a huge area of sea. I have made a stick chart to clarify the geography and identify the atolls that the USA used for military purposes. There is a bit more about stick charts below.


The Enewetok and Bikini [the swimsuit was named after the atoll] atolls were the ones used for testing. Kwajalien is still used by the USA as the the Ronald Reagan Ballistic Missile Defense Test Site. Majuro is the capital of the Marshall Islands. To give some idea of scale; it is 539 miles from Bikini to Ebon, the same distance as from London to Leipzig. The circular calculator in the bottom left is a Time Conversion Computer [see this post].

Testing began on Bikini  in 1946 with the Crossroads tests Two 21 kiloton atomic bombs were detonated. ‘Able’ was an atmospheric test [video] and ‘Baker” an underwater test [video]. baker was exploded at a depth of 27 meters in the middle of a small fleet of ex WW2 vessels. The dangers of radioactivity were not fully understood then and sailors were sent to try a scrub ‘clean’ the highly contaminated vessels.

Testing then moved to Enewetok Atoll for the Sandstone, Greenhouse and Ivy series of tests. After that testing took place on both Enewetok and Bikini until  Operation Dominic in 1962 which involved 36 bombs being detonated above and near Johnston Atoll and Christmas Island.

Both Enewetok and Bikini remain heavily contaminated. Bikini is now a UNESCO World Heritage site. The natives of the Marshall Islands suffered form American operations in the Pacific Proving Ground, but not as badly as the natives of Utah and the mid west suffered from the operations in the Nevada Proving Ground.

Marshall Islands Stick Charts

Probably most of the travel in the Marshall Islands took place between the islands in individual atolls. Bikini Atoll has 23 islands and the central lagoon is 229 square miles. Enewetok has 40 islands and a central lagoon 50 miles in circumference. Navigating within a lagoon would not have been trivial.

Navigating between atolls would in most cases have been both difficult and dangerous. The area bounded by Bikini Utrik, Majuro and Ebon is 165,000 square miles. That is a lot of sea to get lost in. Travelling from Bikini to Enewetok involves a journey of 190 miles and if a navigator missed the atoll it was a long way to the next land.


Navigators were important people who guarded their knowledge. They created stick charts to help them remember the direction of other atolls and the currents and swells that would affect their navigation. The charts consisted of sticks tied to create a frame and shells fastened to the frame to indicate the atolls.

Some stick charts just showed [usually inaccurately] the direction and distance of some other atolls, like this 1884 specimen one from a Swedish Museum.


And this one from the Harvard University’s Peabody Museum.


Others also included sticks to indicate the flow of currents and swells.


Each navigator prepared his own stick chart and probably jealously guarded it from other navigators, just as sailing masters did in the early days of Western exploration.

Probably the navigators used a number of other techniques. Such as following the seasonal navigation of birds, celestial navigation and noting the interferences in air and sea patterns caused by atolls. They might also have taken frigate birds with them. These birds will not land on the water as their feathers will become waterlogged making it impossible to fly. When the navigators  thought they were close to land they may have released a bird, which would either fly towards land or else return to the canoe.

Doctor David Lewis’ ‘We, the Navigators: Ancient Art of Landfinding in the Pacific’ is the classic study of Pacific navigation techniques.


Leave a comment

Filed under Cold War, History

The DNA Multi-sigma Damage Prediction Rule MSIG – 1 Cold War slide rule

The MSIG – 1  Multi-sigma slide rule was produced by the US Defense Nuclear Agency to assist military planners in calculating the probability of damage resulting from a nuclear detonation.

DNA MSIG-1 Multi-Sigma Damage Prediction Rule 2

The rule is 8″ [205 mm] in diameter and  produced by Perrygraf. It was designed by the DNA and is dated April 1987. This rule is very collectable but the hardest to find of all the DNA slide rules. The one shown was never issued and is in mint condition.

DNA MSIG-1 Multi-Sigma Damage Prediction Rule 3

DNA MSIG-1 Multi-Sigma Damage Prediction Rule 4

The MSIG -1 was the last slide rule to be produced by the DNA. After that they only supplied software for use on desktop and hand held machines. A list of the slide rule and software can be found in this post.

The complete package as issued consisted of a binder, hard cover, documentation, slide rule and two floppy disks.

DNA MSIG-1 Multi-Sigma Damage Prediction Rule 1

Leave a comment

Filed under Cold War, Cold War Calculators

The Defense Nuclear Agency’s Cold War calculators

The Defense Nuclear Agency was an offspring of the Manhattan Project and is now part of the Defense Threat Reduction Agency. In its various guises it had many responsibilities connected with America’s nuclear weapons programmes.

In the 1980s and 1990s it produced a series of calculators to help the military plan its nuclear attacks on targets in the USSR and other countries. The US had a list of target Vulnerability Numbers [see this post].  Planners could use these numbers and the DNA calculators to decide whether  a bomber, a submarine launched missile or a ground launched missile be used against a target [they had different levels of accuracy] to achieve a specified level of damage and probability of success.

Vulnerability Numbers 1The first calculators were circular slide rules, designed by the DNA and produced by Perrygraf. These rules are now both very collectable and very rare. A list of these rules is below.

Defense Nuclear Agency Cold War slide rules and software 4This blog has posts on all these. The list is incomplete because the DNA produced a Damage Prediction Rule VN – 1 in 1982 [see this post].

As soon as a introduction of the IBM PC created a technical standard for personal computers the DNA began producing nuclear targeting software programs.  Some of the DNA’ss programs duplicated the functionality of the above slides rules. The Multi-sigma Damage Prediction Rule was produced as both a physical slide rule and as  software programs for hand held and desktop machines.  Programs for a long list of other targeting functions were added to the DNA catalogue.

Defense Nuclear Agency Cold War slide rules and software 2

Defense Nuclear Agency Cold War slide rules and software 3

Leave a comment

Filed under Calculators, Cold War, Cold War Calculators, Uncategorized

Defending Chicago [Part 1] – A New Threat

Nike missile batteries 02

During the 1950s the USA military started to worry that Russian bombers might fly over the Arctic and Canada and drop nuclear bombs on American cities.

The decision to drop atomic bombs on Japanese cities did little to shorten the war but it did create an existential threat to the USA.  Several things  followed from the American’s demonstration that  nuclear bombs worked, that they had some and were prepared to drop them on civilian targets.

1   Other countries would have to have such bombs or be prepared to obey America. Sure enough, in 1949 The Soviet Union detonated Joe -1, its first atomic bomb. Five years before the CIA expected the Soviet Union to have a A bomb.  The bomb was about Hiroshima size.

2   Bombs would get more powerful. In 1952 the USA tested a 10.4 megaton hydrogen bomb, but it was too heavy to be deliverable. In 1953 the Soviet Union tested a hydrogen bomb which had a much lower yield but was deliverable.  Soon both sides had multimegaton hydrogen bombs which were deliverable.

Until the US introduced the world to the nuclear age America had been effectively immune to aerial bombing. Now it wasn’t and the bombs were a lot more powerful. A successful attack could turn the USA into a third world country.


The US military realised that America was almost defenceless.  In a simulated Soviet attack [Operation Tailwind], 94 SAC bombers tested the air defence system of the continental USA by flying over Canada at night, and using electronic countermeasures to simulate a Soviet raid. Only 7 of the planes were spotted by radar and “shot down.

America had no reliable way of detecting approaching Soviet bombers. If incoming bombers were detected there was no good way of destroying them.

It might not even know  it had been attacked. If Los Angeles was destroyed or the SAC base at Homestead in Florida, how long would it take for Washington and SAC at Omaha to realised what had happened?  Probably too long. Even more worrying; what if the USA wrongly believed it was being attacked and started WW3?

In 1961, when tensions were very high during the Berlin Crisis, SAC headquarters in Omaha lost contact with the  Thule radar base in Greenland. A SAC officer called NORAD headquarters in Colorado Springs to find out what was wrong. The line was dead. Both Thule and NORAD were considered key bases that were likely to be hit very early in any Soviet attack. That they were both offline strongly suggested that an attack was in progress. A technical fault seemed unlikely since one base was east of Omaha and the other to the west.

It later emerged that a single AT & T switch in Black Forest, Colorado had failed and cut most of SAC and NORAD’s communications circuits. AT & T had not provided redundant switches, despite have told the US government that it had done so.

General LeMay of SAC thought that spending money on defence was a waste of time since some Russian bombers would always get through. He believed that all the money should be spent on offensive weapons. ‘ If the Soviets launched an attack with 200 bombers and American forces somehow managed to shoot down 90 percent of those planes, the United States would still be hit by at least 20 H-bombs, if not more.’  [Quoted in the excellent  Command and Control. by Eric Schlosser 2013]. Being a psychopath he did not realise that saving even a single American city was worthwhile.

LeMay’s arguments did not prevail and the USA began building its defences.

Leave a comment

Filed under Cold War, History

The Nuclear Bomb Effects Computer Versions 1, 2 & 3

There were three versions of the Nuclear Bomb Effects Computer.  The first was designed by EG&G.

“EG&G, formally known as Edgerton, Münchhausen, and Grier, Inc., was a United States national defense contractor and provider of management and technical services. The company was involved in contracting services to the United States government during World War II and conducted weapons research and development after the war.” Wikipedia.

The calculator was based on test data published in the first edition of the ‘The Effects of Nuclear Weapons’.  The calculator is made of plastic and is 4″ in diameter. A complete set consists of the calculator, a red and white sleeve and an instruction pamphlet.  This cold war calculator is very rare.

Nuclear Bomb Effects Computer V1

Nuclear Bomb Effects Computer V1

Nuclear Bomb Effects Computer V1 02

Nuclear Bomb Effects Computer V1 03

Nuclear Bomb Effects Computer V2

A revised version of the calculator was designed by the Lovelace Foundation. See this post for more information. Like V1 this calculator is very rare.

Nuclear Bomb Effects Computer V2

Nuclear Bomb Effects Computer V3

The third version of the calculator was also designed by the Lovelace Foundation. Its design is much improved over the earlier versions and is based on a revised test data set which was published in the second edition of the ‘The Effects of Nuclear Weapons’. The calculator is 5″ in diameter and is made of plastic. This version is not rare. Copies of the calculator were on public sale for $1 along with the revised edition of the ‘The Effects of Nuclear Weapons’ for $3.  The calculator was used as a prop in the Dr Strangelove film and copies were given away to promote the film. See this post for more information.

Nuclear Bomb Effects Computer V3

Leave a comment

Filed under Calculators, Cold War, Cold War Calculators, History

The Nuclear Club

worlds nuclear club

Note that the US had 31,255 warheads in 1967. See this post.

Leave a comment

January 17, 2016 · 7:50 pm

U.S. Cold War Nuclear Target Lists Declassified for First Time


Screen Shot 2015-12-23 at 20.52.15

“ON JANUARY 25, 1991, General George Lee Butler became the head of the Strategic Air Command. During his first week on the job, Butler asked the Joint Strategic Target Planning Staff to give him a copy of the SIOP. Butler decided to look at every single target in the SIOP, and for weeks he carefully scrutinized the thousands of desired ground zeros. He found bridges and railways and roads in the middle of nowhere targeted with multiple warheads, to assure their destruction. Hundreds of nuclear warheads would hit Moscow—dozens of them aimed at a single radar installation outside the city.

During his previous job working for the Joint Chiefs, Butler had dealt with targeting issues and the damage criteria for nuclear weapons. He was hardly naive. But the days and weeks spent going through the SIOP, page by page, deeply affected him.

For more than forty years, efforts to tame the SIOP, to limit it, reduce it, make it appear logical and reasonable, had failed. “With the possible exception of the Soviet nuclear war plan, this was the single most absurd and irresponsible document I had ever reviewed in my life,” General Butler later recalled. “I came to fully appreciate the truth … we escaped the Cold War without a nuclear holocaust by some combination of skill, luck, and divine intervention, and I suspect the latter in greatest proportion.

Butler eliminated about 75 percent of the targets in the SIOP, introduced a targeting philosophy that was truly flexible, and decided to get rid of the name SIOP. The United States no longer had a single, integrated war plan. Butler preferred a new title for the diverse range of nuclear options: National Strategic Response Plans”

Excerpt From: Schlosser, Eric. “Command and Control.” 2009.      Link

It appears that during the Cold War the defence industries kept churning out nuclear bomb and the military kept trying to find targets for them. If a war had started by accident or design it would have destroyed most life in the northern hemisphere and perhaps triggered a nuclear winter. One lesson is the need to keep the military under very close supervision.

1 Comment

Filed under Cold War, History