<s xml:space="preserve">
The problem pursued in this and many other folios in Add MS 6784 is 'the cutting-off of a ratio',
as set out in Pappus,
<emph style="it">Mathematicae collectiones</emph>
, Book 7. In Commandino's edition of 1588, the problem is stated on page 158v
<ref id="pappus_1588">
(Pappus </ref>
. </s>
<lb/>
<quote xml:lang="lat">
<s xml:space="preserve">
Per datum punctum rectam lineam ducere secantem a duabus rectis lineis positione datis ad data in ipsis puncta lineas,
quæ proportionem habeant eandem datæ proportioni.</s>
</quote>
<lb/>
<quote>
<s xml:space="preserve">
Through a given point, draw a line cutting off line segments from two lines given in position,
to points given in them, which have a ratio the same as a given ratio.</s>
</quote>
<lb/>
<s xml:space="preserve">
Using Harriot's lettering, the problem may be stated as follows.
Given the lines
<math>
<mstyle>
<mi>u</mi>
<mi>e</mi>
</mstyle>
</math>
,
<math>
<mstyle>
<mi>t</mi>
<mi>q</mi>
</mstyle>
</math>
, the point
<math>
<mstyle>
<mi>o</mi>
</mstyle>
</math>
, and the ratio
<math>
<mstyle>
<mi>x</mi>
<mo>:</mo>
<mi>z</mi>
</mstyle>
</math>
, construct the line
<math>
<mstyle>
<mi>o</mi>
<mi>a</mi>
<mi>y</mi>
</mstyle>
</math>
so that
<math>
<mstyle>
<mi>u</mi>
<mi>a</mi>
<mo>:</mo>
<mi>t</mi>
<mi>y</mi>
<mo>=</mo>
<mi>x</mi>
<mo>:</mo>
<mi>z</mi>
</mstyle>
</math>
. There are many variations of the problem according to the relative positions of
<math>
<mstyle>
<mi>u</mi>
<mi>e</mi>
</mstyle>
</math>
,
<math>
<mstyle>
<mi>t</mi>
<mi>q</mi>
</mstyle>
</math>
, and
<math>
<mstyle>
<mi>o</mi>
</mstyle>
</math>
, which Harriot explored in this and other folios. </s>
<lb/>
<s xml:space="preserve">
This example, in Add MS
<ref target="http://echo.mpiwg-berlin.mpg.de/ECHOdocuView?url=/permanent/library/XT0KZ8QC/&start=40&viewMode=image&pn=47">
f. </ref>
<ref target="http://echo.mpiwg-berlin.mpg.de/ECHOdocuView?url=/permanent/library/XT0KZ8QC/&start=50&viewMode=image&pn=55">
f. </ref>
, demonstrates the use of Viète's concepts of zetetic, poristic, analysis, and synthesis. </s>
<s xml:space="preserve">]</s>
</p>
</div>
<head xml:space="preserve" xml:lang="lat">
b.1) De sectione
<lb/>
[
<emph style="bf">Translation: </emph>
On the cutting off of a ]</head>
<p xml:lang="lat">
<s xml:space="preserve">
Data:
<lb/>
<math>
<mstyle>
<mi>u</mi>
<mi>e</mi>
</mstyle>
</math>
.
<math>
<mstyle>
<mi>t</mi>
<mi>q</mi>
</mstyle>
</math>
. lineaæ infinitæ
<lb/>
<math>
<mstyle>
<mi>u</mi>
</mstyle>
</math>
.
<math>
<mstyle>
<mi>t</mi>
</mstyle>
</math>
. termini.
<lb/>
<math>
<mstyle>
<mi>o</mi>
</mstyle>
</math>
. punctum.
<lb/>
<math>
<mstyle>
<mi>x</mi>
</mstyle>
</math>
.
<math>
<mstyle>
<mi>z</mi>
</mstyle>
</math>
.
<lb/>
[
<emph style="bf">Translation: </emph>
Given:
<lb/>
<math>
<mstyle>
<mi>u</mi>
<mi>e</mi>
</mstyle>
</math>
,
<math>
<mstyle>
<mi>t</mi>
<mi>q</mi>
</mstyle>
</math>
, infinite lines.
<lb/>
<math>
<mstyle>
<mi>u</mi>
</mstyle>
</math>
,
<math>
<mstyle>
<mi>t</mi>
</mstyle>
</math>
, endpoints.
<lb/>
<math>
<mstyle>
<mi>o</mi>
</mstyle>
</math>
, a point.
<lb/>
<math>
<mstyle>
<mi>x</mi>
<mo>:</mo>
<mi>z</mi>
</mstyle>
</math>
, a ratio. </s>
</p>
<p xml:lang="lat">
<s xml:space="preserve">
Quæsitum:
<lb/>
Ducere lineam
<math>
<mstyle>
<mi>o</mi>
<mi>a</mi>
<mi>y</mi>
</mstyle>
</math>
<lb/>
Ut fiat:
<math>
<mstyle>
<mi>u</mi>
<mi>a</mi>
<mo>,</mo>
<mi>t</mi>
<mi>y</mi>
<mo>:</mo>
<mi>x</mi>
<mo>,</mo>
<mi>z</mi>
</mstyle>
</math>
.
<lb/>
Hoc fit si ducetur
<math>
<mstyle>
<mi>u</mi>
<mi>a</mi>
</mstyle>
</math>
, vel
<math>
<mstyle>
<mi>i</mi>
<mi>a</mi>
</mstyle>
</math>
, vel
<math>
<mstyle>
<mi>p</mi>
<mi>a</mi>
</mstyle>
</math>
.
<lb/>
Quæritur igitur una, nempe
<math>
<mstyle>
<mi>i</mi>
<mi>a</mi>
</mstyle>
</math>
<lb/>
[
<emph style="bf">Translation: </emph>
Sought:
<lb/>
To draw the ine
<math>
<mstyle>
<mi>o</mi>
<mi>a</mi>
<mi>y</mi>
</mstyle>
</math>
so that
<math>
<mstyle>
<mi>u</mi>
<mi>a</mi>
<mo>:</mo>
<mi>t</mi>
<mi>y</mi>
<mo>=</mo>
<mi>x</mi>
<mo>:</mo>
<mi>z</mi>
</mstyle>
</math>
.
<lb/>
This is done if there are drawn
<math>
<mstyle>
<mi>u</mi>
<mi>a</mi>
</mstyle>
</math>
, or
<math>
<mstyle>
<mi>i</mi>
<mi>a</mi>
</mstyle>
</math>
, or
<math>
<mstyle>
<mi>p</mi>
<mi>a</mi>
</mstyle>
</math>
.
<lb/>
Therefore, one is sought, namely
<math>
<mstyle>
<mi>i</mi>
<mi>a</mi>
</mstyle>
</math>
. </s>
</p>
<p xml:lang="lat">
<s xml:space="preserve">
Interpretatio
<lb/>
<lb/>
[
<emph style="bf">Translation: </emph>
Interpretation of the ]</s>
</p>
<p xml:lang="lat">
<s xml:space="preserve">
Zetetice 1
<emph style="super">a</emph>
<lb/>
Sit iam factum.
<lb/>
Et agatur
<math>
<mstyle>
<mi>o</mi>
<mi>a</mi>
<mi>y</mi>
</mstyle>
</math>
.
<lb/>
fiat:
<math>
<mstyle>
<mi>o</mi>
<mi>q</mi>
</mstyle>
</math>
parall:
<math>
<mstyle>
<mi>u</mi>
<mi>e</mi>
</mstyle>
</math>
.
<lb/>
<math>
<mstyle>
<mi>o</mi>
<mi>i</mi>
</mstyle>
</math>
. parall.
<math>
<mstyle>
<mi>t</mi>
<mi>q</mi>
</mstyle>
</math>
.
<lb/>
agatur recta
<math>
<mstyle>
<mi>o</mi>
<mi>t</mi>
</mstyle>
</math>
quæ secabit
<math>
<mstyle>
<mi>o</mi>
<mi>e</mi>
</mstyle>
</math>
in
<math>
<mstyle>
<mi>p</mi>
</mstyle>
</math>
.
<lb/>
<lb/>
[
<emph style="bf">Translation: </emph>
Zetetic 1.
<lb/>
Let it be already done, and the line
<math>
<mstyle>
<mi>o</mi>
<mi>a</mi>
<mi>y</mi>
</mstyle>
</math>
constructed.
<lb/>
Then make
<math>
<mstyle>
<mi>o</mi>
<mi>q</mi>
</mstyle>
</math>
parallel to
<math>
<mstyle>
<mi>u</mi>
<mi>e</mi>
</mstyle>
</math>
and
<math>
<mstyle>
<mi>o</mi>
<mi>i</mi>
</mstyle>
</math>
parallel to
<math>
<mstyle>
<mi>t</mi>
<mi>q</mi>
</mstyle>
</math>
.
<lb/>
The line
<math>
<mstyle>
<mi>o</mi>
<mi>t</mi>
</mstyle>
</math>
is constructed which cuts
<math>
<mstyle>
<mi>o</mi>
<mi>e</mi>
</mstyle>
</math>
in
<math>
<mstyle>
<mi>p</mi>
</mstyle>
</math>
.
<lb/>
]</s>
</p>
<p xml:lang="lat">
<s xml:space="preserve">
Ergo ad determinatum sectione
<lb/>
eductam est. datur igitur
<math>
<mstyle>
<mi>i</mi>
<mi>a</mi>
</mstyle>
</math>
<lb/>
[
<emph style="bf">Translation: </emph>
Therefore the determination of the section is brought out. Therefore