According to Major Dwyer, who is a high authority on the subject of
bits,--and whose little work should be carefully studied by all
bit-makers,--it seems to be the general rule to have the lower bar or
cheek of the curb-bit twice as long as the upper one; but, as there is
no standard measure for the upper one the other is frequently made too
long. Major Dwyer states that the mouth-piece, for any horse of ordinary
size, should be one and three fourths inches for the upper bar, and
three and a half inches for the lower one. This makes five and one
fourth inches for the entire length of the two bars, from the point at
which the curb-hook acts above to that where the lower ring acts below.
(Fig. 15.) For ordinary ponies the upper bar may be one and a half
inches, and the lower one three, making a total length of four and a
half inches.