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But the most popular one is that these lenses have the power of concentrating the rays of the sun to an almost infinite degree, and then spreading them out again, each individual beam with the concentrated energy of the whole. Some new way of rearranging quanta of energy." "Hmm!" Hilary's brow was wrinkled. For a long moment he stared and thought.

I will now endeavor to explain the general principle by which this phenomenon is utilized in the testing of plane surfaces. Suppose that we place on the lower plate, lenses of constantly increasing curvature until that curvature becomes nil, or in other words a true plane.

Ultron, when so connected with battery terminals, glows with true light under the impact of ultralight, and if in the form of a lens or set of lenses, may be made to deliver a picture in any telescopic degree desired.

Upon the table lay a battered spy-glass, minus lenses, and, nearby, two boxes, one containing dried corn-silk, the other hayseed, convenient for the making of amateur cigarettes; the smoker's outfit being completed by a neat pile of rectangular clippings from newspapers.

Fifteen patents for improvements in sugar manufacture, patents for motors and hydraulic apparatus, for the manufacture of iron and steel, the shaping, embossing, shearing, and cutting of metals, for marine artillery, ordnance, projectiles, ammunition, armor plates, screw propellers, anchors, silvering glass, casting of type, patents for bronze powder, gold paint, oils, varnishes, asphalt pavements, waterproof fabrics, lenses, etc.

The structure of the eye and ear in exact confirmity to the laws of optics and acoustics, shows as clearly as any experiment can show anything, that the source, cause or origin is common both to the properties of light and the formation of the lenses and retina in the eye both to the properties of sound and the tympanum, malleus, incus and stapes of the ear.

The instrument presented to Prince Maurice, and which the Marquis Spinola found in the shop of John Lippershey, the spectacle maker of Middleburg, must have been an astronomical telescope consisting of two convex lenses.

Thus any two lenses used at apertures of F/8, that is at apertures having diameters one-eighth of their respective focal lengths, should be of the same speed, though both lenses and apertures may be very different. In a given lens, the speed varies directly with the area of the aperture admitting the light, that is with the square of the diameter of the aperture.

What do the astronomers think when they predict, at a given hour and place, the passage of a comet, that most eccentric of celestial travellers? What do the naturalists think when they reveal the myriad forms of life concealed in a drop of water? Do they think they have invented what they see and that their lenses and microscopes make the law of nature?

The construction of portrait lenses was next gone into, the influence of the negative element of the back lens being especially noted. A method was then referred to of making a rapid portrait lens cover a very large angle by pivoting at its optical center and traversing the plate in the manner of the pantoscopic camera.