385193r
[Commentary:
This page is part of Harriot's
experiments on refractive colours. Harriot has discovered (on
f. 194) that simple analogy to the glass prism does not provide an adequate secondary cardinal for the water prism, Harriot now applies the entire method of the glass prism workings using the data for the water prism, to calculate the secondary cardinal from scratch. As in that case (see
f. 187) Harriot tries several approximations, before hitting on a 'good cardinal'. ]
De coloribus per angulum aqueum.
[Translation: On colours through a water prism. ]
[Translation: On colours through a water prism. ]
1. ponamus, ut diximus, cardinalem secundarium 48° 20â²
0° 15â² 48â³ 15â´. debet esse 30â²
[Translation: Let us assume, as I said, that the secondary cardinal is 48° 20â².
0° 15â² 48â³ 15â´. It ought to be nearly 30â². ]
0° 15â² 48â³ 15â´. debet esse 30â²
[Translation: Let us assume, as I said, that the secondary cardinal is 48° 20â².
0° 15â² 48â³ 15â´. It ought to be nearly 30â². ]
2. faciamus igitur novum cardinalem
[Translation: And so let us make a new secondary cardinal. ]
[Translation: And so let us make a new secondary cardinal. ]
3. faciamus alterum cardinalem meliorem per proportionem.
Examinatio cardinalis.
Consentit cum observatis.
Bonus igitur
[Translation: Let us make, by means of proportion, another, better cardinal.
Examination of the cardinal.
It agrees with observations.
And so this cardinal is good. ]
Examinatio cardinalis.
Consentit cum observatis.
Bonus igitur
[Translation: Let us make, by means of proportion, another, better cardinal.
Examination of the cardinal.
It agrees with observations.
And so this cardinal is good. ]
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