I wrote:

>>I guess the theory of putting both parts on the left is to allow all the
>>f-holes to face outwards and to keep the violin sound more of a luminous
>>mass.  But there is always the argument that this lies in direct contrast
>>to the setup composers were writing for.

And Len Fehskens wrote:

>Why would the violins be split into firsts and seconds if they were both
>supposed to sound the same?

I'm not sure I understand the question, but I'll try to answer what I
think is the point here.  Namely, if the violins are written in two parts,
playing different notes in other words, what does it matter if they are
together or apart.  That is, if they're playing different parts they by
definition don't "sound the same."

To begin with, just because they are called first and seconds doesn't mean
the violins are playing only two parts.  Composers often divide the parts
within the sections.  That is, the firsts could be playing two parts
between them, or three or four or even more.  I don't mean double (triple
or whatever) stopping but rather that two stands could be playing one part,
two could be playing another, etc.  Obviously, you wouldn't have 12 stands
of firsts sitting in 12 different places or 6 or whatever.  (Though maybe
Stokowski might.  I seem to remember him doing this kind of thing.  I've
certainly seen it done in choruses.)

To the question proper, my explanation, which is by no means official, is
that it is the sound of the instruments we're concerned with when we put
all the violins on the left to create a more coherent or together sound.
No matter how many parts the violins play, they are still violins.  You
do hear the difference in mass when you put all the violins on one side
as opposed to separating first and seconds in what essentially is to
spread the violins across the stage.  To simplify the issue, think of
my instrument, the trombone.  Three trombones sitting together playing
three parts sound vastly different than three trombones spread among the
orchestra playing those parts.  In this case, you aren't necessarily
keeping notes together, but you are keeping like timbres together.  I'm
not a physicist, but I assume, too, that proximity allows for better
interaction between the notes of the same instrument.  It may in fact allow
for better interaction between different instruments, but my assumption is
that keeping like instruments together is more important.

Roger Hecht