Page:Popular Science Monthly Volume 36.djvu/650

632 flat films; the outlines are sometimes very singular, being made up of most eccentric curves in all sorts of combination. In one or two instances these scales overlapped, showing that the disintegration had taken place in a spiral direction (Fig. 10, B). This world of beauty, in both colors and form, was found within the area of one square inch or less, on a small fragment of no special brilliancy to the naked eye.

Brewster describes, in the "Transactions of the Edinburgh Royal Society," some specimens A of ancient decomposed glass, but they must have been in a much earlier stage of decomposition than the Cesnola glass, judging from the figures and descriptions given. He states



 A. a, emerald-green, with strings of bubbles light-green and brilliant, like pale emeralds; b, bronze-gold ground, spots of violet, and bronze-gold rings, ruby, pale vivid blue, and deep sapphire blue; c, partly scaled film, vivid violet, toning down, with spots as above; d, deep violet-blue, like the sky on certain nights; e, speckled gold; f, exquisite violet, with bubbles like pearls, only shaded violet tone.

B. Shape of violet layer as it came off, very thin.

that the experiment had been made of submitting glass to powerful solvents, when, in a short time, circles and other forms, centers of decomposition, began to appear. Here was probably the suggestion which has since been followed in the manufacture of our modern iridescent glass. In a piece of iridescent glass, brilliant at first, but which has been growing more brilliant for several years, I find a number of distinct centers of disintegration, showing the process, whether by art or by time, to be identical in kind.

question involved in the problem of air navigation is regarded by Mr. E. N. Lewis as simply one of increasing power without increasing the weight of the apparatus by which the power is applied. The supposition that the vehicle must be lighter than the air, on which experiment has mostly proceeded, is a mistaken one. "A bird can fly, not because it is comparatively light in weight (for it is not), but because it is strong." The successful air-ship will be a large structure, very light in weight compared with its strength, but many times heavier than the air it displaces, and propelled by machinery capable of developing enormous power. "The skill which has produced . . . the modern bicycle will not find the task of designing such a structure too difficult."