Opticks: or, a treatise of the reflexions, refractions, inflexions and colours of light / Also two treatises of the species and magnitude of curvilinear figures.

  • Newton, Isaac, 1642-1727.
Date:
1704
Catalogue details

Licence: Public Domain Mark

Credit: Opticks: or, a treatise of the reflexions, refractions, inflexions and colours of light / Also two treatises of the species and magnitude of curvilinear figures. Source: Wellcome Collection.

    49/406 (page 39)
    ■ [39] of 45 degrees, A its Redangular Vertex, F M a beam of the Sun’s Light let into a dark Room through a hole F one third part of an Inch broad, M its Incidence on theBafe of the Prifm,M G a lefs refradled Ray, M H a more refradt- ed Ray, M N the beam of Light reflected from the Bafe, V X Y the fecond Prifm by which this beam in paffing through it is refra(5i:ed, N t the lefs refradled Light of this beam, and N p the more refrad:ed part thereof. When the firft Prifm A B C is turned about its Axis according to the order of the Letters ABC, the Rays M H emerge more and more obliquely out of that Prifm, and at length after their moft oblique Emergence are refle<5led towards N, and going on to p do increafe the number of the Rays N p* Afterwards by continuing the motion of the firft Prifm, the Rays M G are alfo reflected to N and increafe the number of the Rays N t. And therefore the Light M N admits into its Compofition, firft the more Refrangible Rays, and then the lefs Refrangible Rays, and yet after this Compofition is of the fime Nature with the Sun’s immediate Light F M, the Reflexion of the fpecular Bafe B C caufing no Altera¬ tion therein. Exper, lo. Two Prifms, which were, alike in fhape, I tied fo together, that their Axes and oppofite Sides being Parallel, they compofed a Parallelopiped. And, the Sun Alining into my dark Chamber through a little hole in the Window-Aiut, I placed that Parallelopiped in his beam at fome diftance from the hole, in ftich a pofture that the Axes of the Prifms might be perpendicular to the incident Rays, and that thofe Rays being incident upon the firft Side of one Prifm, might go on through the two contiguous Sides of both Prifms, and emerge out of the laid Side of the fe¬ cond Prifm. This Side being Parallel to the firft Side of the firft Prifm , caufed the emerging Light to be Parallel to