From the June 12, 1937, issue


When engineers began asking themselves, a short while ago, what the Colorado River was going to do with itself and its channel after it has “gone through the works” at Boulder Dam, they did not try to answer it at Boulder. They came back to Washington, D.C., and in the laboratories of the National Bureau of Standards, they built a wooden river. It didn’t look at all like the Colorado at Boulder Canyon, to be sure, but it did incorporate the particular factors that were giving concern to the engineers.

What they most wanted to know, in the particular downstream problem at Boulder Dam, was what the Colorado waters would do to the bottom of the river. Would the “scour” be faster or slower, now that the water gushes forth without the heavy load of silt it bore in the days before the dam was built?

For the water that comes out at the foot of the dam at Boulder—or of any dam, for that matter—is not the same as water in pre-dam days. A rapidly flowing river always carries along with it a considerable amount of mineral particles—sand and silt. The faster it flows, the larger are the individual particles that it can carry, and also the larger is the total load.

When a dam is thrown across such a river, creating an artificial lake, the river behaves just as it does when it flows into the still water of a natural lake, or of the sea. It loses its velocity, and thus becomes unable to carry its load of mineral particles. The larger ones drop out first and the finer particles later. A delta is formed; the reservoir begins to silt up. The water becomes very much clearer than it was in the old original stream; only the invisibly fine particles, which are in what is technically known as the colloid state, remain in suspension as the water leaves the dam.


The erratic fluctuations in brightness of the tiny planet Eros that have puzzled astronomers for 4 decades and made the body one of the most mysterious in the heavens, have been explained by Fletcher Watson, young research fellow of the Harvard Observatory.

The solution, he says, lies in the fact that instead of having the usual round form that characterizes the Earth and other planets, Eros is shaped like a huge brick.

Revolving end over end, showing first a small end and then a large side, Mr. Watson believes, the planet appears to have rapid changes in brilliance. At other times, he says, the body whirls about with a large, flat side toward the Earth, and this accounts for its occasional periods of constant brightness.

Add to this Mr. Watson’s discovery that Eros is revolving “backwards,” and it is even more understandable why its erratic fluctuations in light have baffled astronomers.


Lying abed, sick or wakeful, in a room papered in a prominent pattern may lead one to believe that the ways a wallpaper pattern can be varied are limitless.

Take it from those who know—not wallpaper manufacturers but crystallographers of the Massachusetts Institute of Technology—that there are only 17 different ways in which the basic design can be repeated on the paper.

This science of design is a sort of by-product of a more intricate task, the study of crystal structure. Each crystalline compound in chemistry is a structure of atoms. The tiny crystals, whose atoms can be detected only by powerful instruments, can be thought of as three-dimensional wallpaper. In three dimensions, or space, patterns can be arranged in 230 different ways, as contrasted with the 17 of repeating a given motif on a plane or two-dimensional surface.

The more complex problem of crystal structure is important in understanding nature’s or man-made chemical compounds so useful in medicine, industry, and other fields. In these compounds, the atoms composing them may be as close together as one ten-trillionth of an inch. Scientists studying photographs of X rays diffracted by crystals, which reveal the patterns, must be able to measure to one five-hundredth of an inch on the photographic film.

The two-dimensional patterns are not confined to wallpaper. They may be found in neckties, dresses, tiling, textile weaves, prints on linoleum, carpets, etc. Professional designers and those who like to work out such puzzle problems just for the fun of it will be interested in studying the article about wallpaper and atoms that appears in the Technology Review (June 1937) written by Prof. M.J. Buerger and J.S. Lukesh.

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