A slide rule is a hand-operated mechanical calculator consisting of slidable rulers for evaluating mathematical operations such as multiplication, division, exponents, roots, logarithms, and trigonometry. It is one of the simplest analog computers.
In the United States, the slide rule is colloquially called a slipstick.
English mathematician and clergyman Reverend William Oughtred and others developed the slide rule in the 17th century based on the emerging work on logarithms by John Napier. It made calculations faster and less error-prone than evaluating on paper.
By Autopilot – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=31387894Wikipedia
One slide rule remaining in daily use around the world is the E6B. This is a circular slide rule first created in the 1930s for aircraft pilots to help with dead reckoning. With the aid of scales printed on the frame it also helps with such miscellaneous tasks as converting time, distance, speed, and temperature values, compass errors, and calculating fuel use. The so-called “prayer wheel”[1] is still available in flight shops, and remains widely used. – Wikipedia
During the Apollo missions, an on-board computer and large computers on Earth performed the critical guidance and navigation calculations necessary for a successful journey. In addition, crews carried a slide rule for more routine calculations. NASA chose a 5-inch, metal rule, model “N600-ES,” manufactured by the Pickett Company for their use. It was a model that was popular among engineers, scientists and students at the time. No modifications were needed for use in space.
This rule was used by the crew of Apollo 13, in April 1970.
The Virtual Slide Rule Museum is an incredibly comprehensive and entertaining site.
After spending a few minutes at the museum, you begin to appreciate how thoughtful and serious the curators are.
Through the photo galleries you realize what an important object the slide rule is in world history (cold war, advance of technology, early STEM, education, social clubs, even entertainment).
The Internet museum is a registered 501(c)3 non-profit. Although a small organization, it appears to have an engaged board, and a 100 rating for Culture and Community on Charity Navigator, and is current with the IRS.
Want to see what a Soviet Era slide rule looks like? No problem! Australian slide rules? No problem! Comics, cartoons, and raccoon with slide rules? No problem!
Need the user’s guide for your 1919 A. Lietz slide rule? No problem!
1950 Prairie View A&M Carrollton HS, TX (1960) Slide Rule Club 1941 USMA Cadets w/Slide Rules Betty Lou Bailey (1929-2007), Mechanical engineer, worked for 44 years at General Electric (picture c1950-1959) in hydropower applications. River preservationalist. SWE Fellow and Pioneer.
The museum even documents the bamboo slide rule manufacturing from the early 20th century:
Mas Macho Hyper-masculine Alpha Nerd Site
[1] Prayer Wheels
The E6B flight computer is a form of circular slide rule used in aviation. It is an instance of an analog calculating device still being used the 21st century.
In addition to the circular dead- reckoning device, prayer wheels also refer to the Tibetan Buddhist devotional tool. It is unclear which was invented first.
A prayer wheel is a cylindrical wheel (Tibetan: འཁོར་ལོ།, Wylie: ‘khor lo, Oirat: кюрдэ) on a spindle made from metal, wood, stone, leather, or coarse cotton, widely used in Tibet and areas where Tibetan culture is predominant.
Traditionally, a mantra is written in Ranjana script or Tibetan script, on the outside of the wheel. The mantra Om mani padme hum is most commonly used, but other mantras may be used as well.
There is a connection between Tibetan prayer wheels and Arthur C. Clark’s famous short story, The Nine Billion Names of God – the ways we think about our relationship with a supreme being.
In a Tibetan lamasery, the monks seek to list all of the names of God.
By Afifa Afrin – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/ind ex.php?curid=56997783
In 2003, Clarke reported having been told that the Dalai Lama had found the story “very amusing”.
Arthur Clarke’s 1952 sci-fi story, “The Nine Billion Names of God,” tells the story of two cynical Manhattan computer programmers in the early days of the industry, who were hired by Tibetan monks to write a program to spit out every possible permutation of a sequence of random letters. According to their Tibetan belief, when all of the nine billion names of God have been discovered and then recorded within the sacred books, history will come to an end, because the natural world will have fulfilled its purpose of revealing all facets of God.
But in particular I enjoy the unexpected irruption of the sacred in a thoroughly secular space. – Jason Baxter
A Comeback for The Rule?
We all recall the collaboration between Martha Stewart and Snoop Dogg to promote a line of abacus-based furniture and jewelry. Perhaps they can be enticed to promote a line of slide rule lawn ornaments?
These guys are great collaborators….
Leave No Turn Unstoned
We couldn’t resist the temptation of the AI-text-to-image prompt “Mas Macho Hyper-masculine Alpha Nerd”.
