I have heard two things on this but I would think that there a definitive answer. A wind (Aeolean) harp has strings just above the sound board and uses just wind to vibrate the strings. Some say the wind should be parallel to the sound board so the string vibrates perpendicular to the sound board. The pro is that you can easily funnel the wind across the strings with a lid that leaves a small gap above the soundboard; the con is that the turbulence created by the first string will weaken the wind over the rest of the strings.
The second is that the soundboard is perpendicular to the sound board. Now the strings vibrate parallel to the sound board (like on a guitar) and the wind is equally strong across all of the strings.
So according to physics, which is best for producing a strong sound?