in the exact thickness at
those places.

This being done, and the places marked levelled down, using spoke
shaves, flat gouge No. 50, and rough sandpaper 3, take again the
large calipers and go over the whole as before, but more carefully;
and do this time after time, until the plate is accurately gauged
from five-thirty-seconds of an inch centre to the diminution of
about a good sixteenth--say one-twelfth of an inch at the edges. My
way of working has always been thus, in preference to using what
people call "indicating calipers"; and my advice to you is, do
likewise, for you not only get over your ground more nimbly, but you
can get from your centre more accurately, I maintain, gradation of
thicknesses. I give you what I have proved the best thicknesses for
my backs, and am pleased to do so to all the world; but if you care
to try a hair or two thinner in the centre, adding those hairs to
the edges, do so; you will not lose in energy, but you will in
timbre, a trifle.

Before finally quitting this hollowing out of the back, gauge for
the last time, then use fine sandpaper, and leave no mark of any
tool whatever, as by clean work you will be judged.

This question of thicknesses is an important one, but applies more
to the belly than the back; and I shall have more to say on this
head when I get to that soundboard, merely adding now that the back
must never be weak in wood, yet, at the same time, never so strong
that a woody tone is the result, inevitable, as the timbre quality
is scarcely developed, and without that I never care for it.

It is desirable at this stage that I point out to you how the inner
edges of the back are rounded before the ribs are fixed. I use file
No. 6, half round, flat side to the wood first, turning to the round
side for finish. When at the corners, I employ knife No. 8 in
cutting where the file would not do it so well in the early stage,
and this file not at all nicely for finish, so I employ a smaller
one, No. 9, to these corners, the other all over the rest of the
wood, cleanly doing the work so that about one-sixteenth only of the
inner edge is rounded off. Then No. 1 sandpaper is used to finish
off the work done, and the next stage is glueing on the end blocks,
preparatory to fixing the ribs as they get made--of which, later.

So, for the present, I leave the back, and take up the wood you will
remember I selected for the front table, or belly, and devote to it
a separate section