Optics. Ptolemej

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Ptolemej has received value of hades and refraction of a ray of light at transition from air in water as follows. It took a circle with gradusnymi divisions and has shipped it in water precisely half. On a circle it has put two indexes, and then has strengthened a direct core in such a manner that it connected two indexes. Ptolemej has resulted the table of the received results and, apparently, it was satisfied with the invention of a way of measurement of refraction, without having established any parity between hades and refractions.

It used precisely same method for studying of refraction of light in glass, having made the glass semicylinder and having used it also for measurement of refraction from water to glass. This method was inconvenient that for each value of a hade of a beam the prism was required provided that all of them are made of identical glass. Whether could Ptolemej open by means of these results the refraction law? It is impossible to suppose hasty that, so far as results have been received, it was possible to deduce from them and known laws.

Now we attribute opening of the law of refraction in its modern kind of Snellu (1580-1626). The Snellovsky conclusion, unfortunately, not remained, almost for certain was theoretical. Descartes who has again formulated the law of refraction in 1638, has appropriated to it a name of Snella. We follow to this day tradition and we leave to the refraction law it is a name. Though, possibly, it Ario (1560-1621) who took a glass prism even earlier has opened and had it so that surface AV was perpendicular to line PQR spent on a table.

Thus, he knew that surface AV should not have a beam deviation. He looked along straight line PQ, and the friend asked to move pin S until it will occupy such position that, looking at it through a prism, he started to see it in direction PQ. Knowing refracting corner of a prism, it could then calculate hades and refractions. Having done the same experiment with the several prisms having various corners, it also has received result which we use and until now. Received Ario value (sinz/sinr) is equal 1/0,6528703.