Bygrave slide rule

The Bygrave slide rule is a slide rule named for its inventor, Captain Leonard Charles Bygrave of the RAF. It was used in celestial navigation, primarily in aviation. Officially, it was called the A. M. L. Position Line Slide Rule (A.M.L. for Air Ministry Laboratories).[1]

Bygrave A.M.L. Position line slide rule Mk. IIA serial No. 355

It was developed in 1920 at the Air Ministry Laboratories at Kensington in London and was produced by Henry Hughes & Son Ltd of London until the mid-1930s. It solved the so-called celestial triangle accurately to about one minute of arc and quickly enough for aerial navigation. The solution of the celestial triangle used the John Napier rules for solution of square-angled spherical triangles. The slide rule was constructed as two coaxial tubes with spiral scales, like the Fuller slide rules, with yet another tube on the outside carrying the cursors.[1]

During the Second World War, a closely related version was produced in Germany by Dennert & Pape as the HR1, MHR1 and HR2.[1]

Famous users

Sir Francis Chichester was a renowned aviator and yachtsman. He used a Bygrave Slide Rule as an aid to navigation during flights in the 1930s, one of which was the first solo flight from New Zealand to Australia in a Gipsy Moth biplane. He later completed a round the world cruise in his yacht Gipsy Moth IV. This was the first solo circumnavigation using the clipper route. Sir Francis Chichester wrote about these exploits in his autobiography, entitled The Lonely Sea and the Sky.[2]

gollark: ```pythonimport argparse,subprocess,random,stringparser = argparse.ArgumentParser(description="Compile a WHY program using WHYJIT.")parser.add_argument("input",help="File containing WHY source code")parser.add_argument("-o","--output",help="Filename of the output executable to make",default="./a.why")parser.add_argument("-O","--optimize",help="Optimization level",type=int,default="0")#parser.add_argument("-d","--drawkcab",help=".sdrawkcab elif ecruos YHW eht ssecorP")args = parser.parse_args()def randomword(length): letters = string.ascii_lowercase return ''.join(random.choice(letters) for i in range(length))def which(program): proc = subprocess.run(["which",program],stdout=subprocess.PIPE) if proc.returncode == 0: return proc.stdout.replace(b"\n",b"") else: return Nonedef find_C_compiler(): compilers = ["gcc","clang","tcc","cc"] for compiler in compilers: path = which(compiler) if path != None: return pathdef build_output(code,max): #if args.drawkcab: code = code[::-1] C_code = f"""#define QUITELONG long long intconst QUITELONG max = {max};int main() {{ volatile QUITELONG i = 0; // disable some "optimizations" that RUIN OUR BEAUTIFUL CODE! while (i < max) {{ i++; }} {code}}} """ heredoc = randomword(100) devnull = "2>/dev/null" shell_script = f"""#!/bin/shTMP1=/tmp/ignore-meTMP2=/tmp/ignore-me-tooTMP3=/tmp/dont-look-here cat << {heredoc} > $TMP1{C_code}{heredoc}sed -e '1,/^exit \$?$/d' "$0" > $TMP3chmod +x $TMP3$TMP3 -x c -o $TMP2 $TMP1chmod +x $TMP2$TMP2exit $?""".encode("utf-8") with open(find_C_compiler(),"rb") as f: return shell_script + f.read()with open(args.input,"r") as f: contents = f.read() looplen = max(1000,(2 ** -args.optimize) * 1000000000) code = build_output( contents, looplen ) with open(args.output,"wb") as out: out.write(code)```
gollark: (and so, code gold was invented)
gollark: Maybe if I compress it manually a bit...
gollark: OH COME ON, this code is less than 2000 characters. Stupid DIsqord.
gollark: Clyde says `Your message could not be delivered because you don't share a server with the recipient or you disabled direct messages on your shared server, recipient is only accepting direct messages from friends, or you were blocked by the recipient.`. Stupid Clyde.

See also
  • Otis King's Patent Calculator

References
  1. "Position Line Slide Rules" (PDF).
  2. Chichester (2006). The Lonely Sea and the Sky. Summersdale Publishers.
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