hand with the cylinders, A A, and on the other with D. The result of
this is that every displacement upward of the top cylinder corresponds
to a different position of the intermediate shaft, and one that is
always equidistant from the centers of the cylinders, A A, thus securing
a constant gearing of the wheels in all the positions of the cylinders,
A A.

The diagram in Fig. 7 shows the relative displacements of all these
parts, as well as those of the scraper guide, C. The diameter to be
obtained is determined beforehand by the two contact screws, P.

The whole thus regulated, the bar of iron, still very hot, coming from
the ordinary rollers, is straightened up, if need be, by a few blows of
a hammer, so that it may roll forward over the pavement, N, between the
rounding cylinders, A A; these being held apart sufficiently to allow
of its easy introduction. Next, a few revolutions of the winches that
control the screws suffice to lower the upper cylinder to the exact
position limited by the contact screws, P, and the bar is rolled between
the two cylinder tables with a constant velocity in the generatrices. As
a consequence, the number of revolutions made is so much the greater in
proportion as the diameter of the shaft is smaller with respect to that
of the cylinders.

It should be remarked that the bar, during its rotation under pressure,
is held by the guide, C, so that its diagrammatic axis (Fig. 7) exceeds
the line, A A, joining the centers of the cylinders just enough to
prevent its escape to the opposite, and so that the pressure upon the
said guide (which performs the role of scraper) is merely sufficient to
detach the scales which form during the operation.