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folding doors, & without any sham front pipes
but in there stead within the Doors let there be
some neat fret work (painted as the Case) which
will serve to conceal the pipes when the doors are
open, & at the same tiem suffer a sufficient
quantity of sound to escape; & therefor no
lining of any sort can be allowed to the part
of the Work, and therefor will be necessary that
the top of the Case be so contrived, that it may be
taken off with ease, & that the fret work also
may let in & ^ take out at pleasure The compass
of the Keys must include double G in the Bass
& E in alt in the treble, which part of the work
must be finished in a neat & masterly
manner Two stops only are required &
both to be stoped Diapason made of wood,
they must be unisons & in Concert pitch,
to each of them must belong a slide or
Register to open or shut the pipes in one Motion
The erronious principle on which the Bellows of
an organ are constructed, renderes it
utterly impracticable to tune the pipes with
any degree of accuracy; in support of this
assertion I beg leave to off what follows,
& Doubt not that you'll join with me in
opinion I tuned two C's a Octave, &
procured a perfect agreement between
them when the Bellows had parted with one third
of their Wind; & when about half was
exausted the octave became imperfect;
but before the wind was quite spent, the
Notes agreed again Not it is evident
that this variation did not arise from any change
the pipes under went, but from the different
degrees of force with which the weight on
the Bellows prest the air into them The truth
of this will further appear from considering in
what manner the Bellows are made Two boards
of equal size placed one above the other,
are