Subject: Re: [HM] Indian astronomy and mathematics
From: Dinesh Maheshwari (dsm@cypress.com)
Date: Wed Feb 16 2000 - 22:29:34 EST
Dear Milo and HM Listmembers,
Regarding the most recent note in which you(Milo) wrote :
> As I read the historical record, Dinesh's 1350 BC suggestion
> for the use of a sidereal calendar is logical, and well outlines.
> I could someday see the date pushed back to 1450 BC, but probably
> not much more.
The "Vedanga Jyotisha" (VJ) is a "limb of the Vedas with a
compilation/explanation of the astronomy" used in the Veda; the
RigVedic recension of VJ refers to RigVedic astronomy and the
YajurVedic recension of the VJ refers to Yajurvedic astronomy. So
even though the VJ itself dates to prior to 1350BC, it's contents
were already applied even earlier.
As a side note, the "vedangas" are considered to be "smrti-prasthana"
i.e. additional supplementary presentations of principles in the Vedas
("shruti-prasthana").
The RigVeda (RV) (4300-4000BC) already refers to the 27 lunar mansions -
nakshatra divided into 12 groups of 2 to 3 nakshatra each corresponding
to 12 months in the nakshatra (sidereal) year. RV 10.90 refers to the
"Purusa" used for design of falcon altar; the design of the falcon
altar symbolizes all the three years : sidereal, solar and lunar.
The Satapatha Brahamana (SB) (dated by astronomical event dating
to 2300BC) refers to sidereal year (SB 7.1.1.32 and SB 7.3.2.9)
and refers to the design of falcon altar (SB 6.1.1.1-3, SB 7.1.1.34)
and to the 101 1/2 fold altar for the 94th year of the 95 year
nakshatra and solar year synchronization.
Nidana Sutras, around the same time as SB, also explicitly refers to
the sidereal year.
Baudhayana Shrauta Sutra (BSS) (dated to 2300-2200BC) - BSS5.6
explicitly gives the formula for the m th augmentation of the falcon altar
in the cycle of 95 year for synchronizing nakshhatra and solar year
to be x**2 = 1+(2m/15) where x**2 is a "square purusa".
> Dinesh's 1/6th of a degree reading of the sky became ONLY available
> during the time that telescopes appears, after 1600 AD (as I read
> the history). As a counter example to the 1/6th of a degree
> suggestion, 10-15 minutes of accuracy is the best that I have read
> than ancients took single 'readings's of solar and sidereal star
> clocks. Improved accuracies, needed for longitude computations (after
> Eratosthenes conducted his 'well experiment) had to wait for the
> telescope.
I think that there might be a bit of confusion with the units because
we seem to be agreeing rather than disagreeing, that is, if I have
comprehended correctly that you agree that the ancients were able to
measure with an accuracy of 10-15 minutes.
1 degree corresponds to 60 arc minutes. So 1/6 of a degree will
correspond to 10 minutes.
I have in the past made the casual mistake of using decimal
arithmetic, just because decimal arithmetic comes more naturally in
day to day applications, rather than the sexagesimal arithmetic while
converting to minutes etc. I wonder if you happened to do the same.
Best Regards,
Dinesh
PS : An erratum in my previous post :
"Perhaps it is already evident to you that my previous
post was not a response to Kim Plofker; I had read KP's post
before posting my previous post."
should read
"Perhaps it is already evident to you that my previous
post was not a response to Kim Plofker; I had NOT read KP's post
before posting my previous post."
--
Dinesh Maheshwari
Advanced Design Methods
Cypress Semiconductor
San Jose, CA , USA
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