Names of the Various Parts.
The long strips, four in number, which form the front and rear edges
of the upper and lower frames, are called the horizontal beams. These
are each 20 feet in length. These horizontal beams are connected by
upright strips,
4 feet long, called stanchions. There are usually 12 of these, six on
the front edge, and six on the rear. They serve to hold the upper plane
away from the lower one. Next comes the ribs. These are 4 feet in
length (projecting for a foot over the rear beam), and while intended
principally as a support to the cloth covering of the planes, also tend
to hold the frame together in a horizontal position just as the
stanchions do in the vertical. There are forty-one of these ribs,
twenty-one on the upper and twenty on the lower plane. Then come the
struts, the main pieces which join the horizontal beams. All of these
parts are shown in the illustrations, reference to which will make the
meaning of the various names clear.