# VMs: Re: Random discoveries in the library

```    > I cannot find a single copy of this figure on any
> of my old pages. Even the photocopy has gone missing.
> I know that Dennis had a copy too, for a while, and
> somewhere in the mailing list archive there is a
> reference to another web page with the same figure
> stating it is actually part of the VMs. (Jim Reeds
> found that one).

It took some searching, but I found a copy of it in my cache of
Voynichanea (which is sort of like my desk, only several orders of
magnitude bigger):

http://www.ic.unicamp.br/~stolfi/voynich/misc/rene-astro-diag.gif

> the [symbol] for Aries (a V with an under- score) looks exactly
> like the first red doodle on VMs f1r.

Yes.  The VMS author must have thought so too. ;-)

> Didn't Gauss (well post-VMs) invent a way to predict
> the dates of Easter using a method involving
> prime numbers, a.o. 17?

Hmmm... Well, the usual algorithm is based on a *19* year cycle. It
uses other divisors, but mostly to account for leap years and the
Gregorian change, and to find the month and day-of-week:

http://aa.usno.navy.mil/faq/docs/easter.html

c = y / 100
n = y - 19 * ( y / 19 )
k = ( c - 17 ) / 25
i = c - c / 4 - ( c - k ) / 3 + 19 * n + 15
i = i - 30 * ( i / 30 )
i = i - ( i / 28 ) * ( 1 - ( i / 28 ) * ( 29 / ( i + 1 ) )
* ( ( 21 - n ) / 11 ) )
j = y + y / 4 + i + 2 - c + c / 4
j = j - 7 * ( j / 7 )
l = i - j
m = 3 + ( l + 40 ) / 44
d = l + 28 - 31 * ( m / 4 )

The algorithm may be due to Gauss, but knowledge of the 19-year cycle
is certainly much older.

All the best,

--stolfi

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