to each part to facilitate the
understanding of it, to this first part certain general
notes are prefixed, to begin with, for the more plain
understanding of the whole Register.

Be it noted, then, first, that this whole Library is
divided into nine several classes (Distinctions), marked
according to the nine first letters of the alphabet,
which are affixed to the classes themselves, in such a
way that A marks out to him who enters the first Class,
B the second, C the third, and so on in order. Each of
the said nine classes, moreover, will be seen to be
divided into seven shelves (grades), which are also
marked off by the addition of Roman numeral figures,
following the letters which denote the classes. We begin
the numbering of the shelves from the bottom, and
proceed upwards so that the bottom shelf, which is the
first, is marked thus, I; the second thus, II; the third
thus, III; and so the numbering goes, on up to
seven[351].

In addition to this, the books of the Library are all of
them marked on each leaf with Arabic numerals, to
facilitate the ascertaining of the contents of the
volumes.

Now since many of the volumes contain a number of
treatises, the names of these treatises, although they
have not always been correctly christened, are written
down under each volume, and an Arabic numeral is added
to each name shewing on what leaf each tract begins. To
this number the letter A or B is subjoined, the letter A
here denoting the first page of the leaf, and the letter
B the second. The books themselves, furthermore, have
their class-letters and also their shelf-marks inserted
not only outside on their bindings, but also inside,
accompanying the tables of contents at the beginning. To
such class-letters a small Arabic figure is added which
shews clearly what position the book occupies in the
order of placing on the shelf concerned.

On the second, third, or fourth leaf of the book, or
thereabouts, on the lower margin the name of the book is
written. Before it are entered the above-mentioned
class-letters and shelf-numbers, and after it (a small
space intervening) are immediately set down the words
with which that leaf begins, which I shall call the
proof of investigation (_probatorium cognitionis_). The
Arabic figures next following