Pike's illustrated descriptive catalogue of optical, mathematical and philosophical instruments Volume 2; manufactured, imported, and sold by the ... affixed at which they are offered in 1848 - Softcover

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1848 Excerpt: ...Compound Prisms.--Prisms are sometimes formed of different kinds of glass, as crown, flint, and plate glass, for showing their different refractive powers. Price, $3.00. Instrument for the Recomposition Fig.699. of Light.--(Fig. 699.)--This instrument for the recomposition of light, sometimes called a color blender, is conveniently formed in the shape of a large top, about five and a half =g3g niches in diameter, which, by means of a string and handle, may be rapidly spun around for a considerable time. On the surface of the top there is accurately described the proportion of the different colors, which are engraved on a plate, near the centre, while the exterior is filled with colored papers, each color of nearly the color of the spectrum, and occupying the same proportion, viz. violet 80, indigo 40, blue 60, green 60, yellow 48, orange 27, red 45; the whole is varnished to protect it from injury. As the rays of the sun may be separated into these seven primitive colors, so, by their mixture in due proportions, may white be produced. White, therefore, is the mixture of all the colors, as black is the want or deprivation of color; which may be proved by this instrument. Though seven different colore are distinguishable in the prismatic spectrum, yet, upon examining the matter with more accuracy, we shall see that there are, in fact, only three original colore--red, blue, and yellow, for the orange being situated between the red and yellow, is only the mixture of these two; the green, in like manner, arises from blending the blue and yellow, and the violet results from the blue and red. Price, $1.00. Glass Box for Experiments on Refraction.--(Fig. 700.)--This consists of a metallic box, open at top, from 8 to 14 inches long, and from 5 to 9 inches wide, havi...