increased to six times the length. If the two are considered as
springs, it will be seen that d is much less likely to be broken by
a blow or strain.

The remedy for the flimsy bed is the box section; the remedy for the
flimsy planer table is the deep box section, and with this advantage,
that the upper edge can be made to shelve over above the reversing
dogs to the full width between the housings.

The parabolic form of housing is elegant in appearance, but
theoretically right only when of uniform cross section. In some of the
counterfeit sort the designers seem to have seen the original Sellers,
remembering the form just well enough to have got the curve wrong end
up, and knowing nothing of the principle, have succeeded in building a
housing that is absolutely weak and absolutely ugly, with just enough
of the original left to show from where it was stolen. If the housing
is constructed on the brace plan, should not the braces be straight,
as in the old Bement, and the center line of strain pass through the
center line of the brace? If the housing is to take the form of a
curve, the section should be practically uniform, and the curve drawn
by an artist. Many times housings are quite rigid enough in the
direction of the travel of the table, but weak against side pressure.
The hollow box section, with secure attachment to the bed and a deep
cross beam at the top, are the remedies.

Raising and lowering cross heads, large and small, by two screws is a
slow and laborious job, and slow when done by power. Counterweights
just balancing the cross head, with metal straps rather than chains or
ropes, large wheels with small anti-friction journals, and the cross
head guarded by one post only, changes a slow to a quick arrangement,