The .618 comes from Fibonacci's series, or the Golden Section.
Architects have used the ratio of 1.618 to 1 (same as .618) for thousands of years.
For some reason human beings find it aesthetically pleasing.
Anyway, Fibonacci's series goes like this:
1+2=3, 2+3=5, 3+5=8, 5+8=13, 8+13=21, and on and on.
See the pattern?
If one divides the next lower number into the next higher number, one gets closer and closer to 1.618 as one gets higher in the series.
This number, 1.618 has many other amazing properties and I recommend doing an internet search for the Golden Section or Phi.
Try this:
http://evolutionoftruth.com/goldensection/goldsect.htm
In any event, some years back I undertook the design of an historically accurate biblical sword, trying to work from the evidence available.
Eventually I had the sword made and it appeared as part of an article written by me in the October 2000
Knives Illustrated as the
Sword of Ehud.
I had very strong evidence that this sword measured 13.5", or one
gomed, a measure derived from the 18" biblical measure called a cubit.
(13.5" sounds short for a sword, I know; bear with me)
At the same time I read on the Randall Made Knives site that they considered a knife, specifically the #1 and #2, made to the proportions described earlier (actually, 13 X 8 X 5) as the best handling combat or fighting knife.
I immediately recognized the 13 X 8 X 5 numbers as part of the Fibonacci series.
Therefore, I incorporated the number 1.618 or .618 in my design wherever I could.
In this case, I designed what looks like a dagger.
However, early on in the fabrication of the knife/sword, Gene Osborn, the maker, remarked that the knife felt unusually powerful for a dagger.
Now that I have the finished knife, I can attest to its unusual balance and "power."
Now, the short sword in question belonged to a Benjamite judge and warrior named Ehud, who used it to assassinate a king.
We know that he strapped it to his thigh and smuggled it past the king's body guards.
We also know that Ehud described it as one cubit in length.
Well in those days they used the word cubit to mean both the gomed, 13.5", and the cubit, 18".
So, I decided to make the same exact sword myself, this time 18" but scaled exactly to the 13.5" version.
This results in an 11.124" blade and a 6.876" handle.
Amazingly, this knife also handles like lightning and will chop down a telephone pole (mild exaggeration).
Here comes the interesting thing about 18", or a cubit.
Remember, the gomed equals the inside of the forearm.
The cubit then equals the distance from the outside of the elbow to the outside of the curved middle finger.
This distance has great import to archers, although I cannot say why; but it does.
This distance also happens to equal the distance from the center of rotation of the hip to the center of rotation of the knee.
In a small person or a large person, that distance may vary but the distance from knee to hip will always equal the distance from outside elbow to outside middle knuckle.
Gomed eguals inside and cubit equals outside.
One can strap a gomed length knife to the inside of one's thigh, and still safely kneel without "painting" the knife; similarly, one can strap a cubit length knife to the outside of one's thigh and still kneel.
Most relevant to this conversation, though, if the maker can cause the knife to balance at the Golden Section, it handles in a manner which one cannot appreciate or imagine until he feels it for himself.
Therefore, I surmised that the Bowie knife, in order to manifest the qualities ascribed to it, must also balance at the Golden section.
So far, I only have two knives which balance exactly at the Golden Section, and they both handle like a dream.
They both also derive their overall lenght from body proportions; I don't how much of a factor this presents, though.
I can only report what I've experienced.
I have to go to bed.
I haven't edited this; I hope it makes sense.