Down-bow
The downward motion of the bow, symbol ⊓.
What it means
The down-bow is the bow motion in which the hand travels from the frog to the tip — the bow, that is, is drawn out and away from the body across the string. Together with the up-bow it forms the basic pair of all bowing on violin, viola, cello and double bass. Because the bow is heaviest at the frog and the arm transmits the most force there, a down-bow usually begins with natural weight and loses substance toward the tip.
In the notation
The down-bow is prescribed with a small square sign above the note, resembling a lying bracket. It stands only where the bowing direction does not already follow from the context: at the beginnings of movements, after rests, at passages with unusual grouping, or when a whole section is to play uniformly. Where no marking is given, the player or the leading of the section decides; in orchestral parts the concertmaster enters the bowings for the strings.
Musical use
The down-bow counts as the heavier, more accented of the two strokes. For this reason it traditionally falls on accented beats, especially on the first beat of a bar; the old rule of the good part of the bar on the down-bow shapes the marking of orchestral parts to this day. March-like, accented or solemn music deliberately uses successive down-bows to give each note the same weight. Conversely, a composer may break the expectation and place an accent on the up-bow to make a passage seem lighter.
Performance practice
See that the down-bow does not automatically become louder merely because the arm brings more weight at the frog. Evenness arises when you give a little more arm weight toward the tip and hold the contact point on the string steady. The elbow leads the motion, the wrist evens it out; a rigid wrist betrays itself at once through a hard attack. Before practising a passage, plan the bowing directions so that the important notes fall on the down-bow and you do not end up stuck at the tip just before an accented spot. Practise a difficult passage deliberately with the bowings reversed as well — this shows how much the sound depends on the bowing.