My early viola bows are not that different from the early violin bows - just a little longer (in principle, as long as the instrument itself), and correspondingly a little heavier.
Here is a rather extraordinary bow of yew, with a snakewood frog:
(I love the sound of this bow - sadly this particular one is not for sale, as the spalted wood - which lends the beautiful wavy patterns - might have a tendency to split. So I'll enjoy it while it lasts!)
This bow is also available in cherry, beech, plum, pear (or Elsbeer), and maple, each with its own characteristic sound and feel. I also a similar bow from snakewood - still articulate and very lively, but with a certain density or focus of sound. Here is one, 66 cm long, 40 grams:
Here is a significantly later model - still with a clip-in frog, but I would estimate appropriate for music from around the middle of the 18th century.