Page:Popular Science Monthly Volume 42.djvu/154

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their surroundings. Experiments with artificial colors showed that both blue and red tended to produce a dark coloration, especially the former; while, strangely enough, painted twigs did not produce the same effect as those whose tints were natural. Mr. Poulton was able to show that the sensory stimulus producing the change did not act through the eye, as in the case of the chameleon, frog, and sole, but through the skin. It consists, moreover, in the formation of definite pigment, and hence is not so rapid as in those animals. It is possible to modify the color of a caterpillar only once or twice in its lifetime.

The past year, said Dr. Alexander Macalister, in the anthropological address at the British Association, had not been fertile in discoveries bearing on questions of popular interest. No new light had been shed on the darkness that enshrouded the origin of man; but in this connection Dr. Louis Robinson had, from a series of observations on the prehensile power of the hands of children at birth, arrived at the same conclusion which Mr. Robert Louis Stevenson deduced from the study of his grandfather—namely, that there still survived in the human structure and habit traces of our probably arboreal ancestry.

Of one hundred and three members of the British Association of last year who were anthropometrically examined at Cardiff, seventy-eight were men, and the mean stature of the whole was sixty-eight inches, being one inch above the average stature of the people of the British Isles.

The third report of the committee of the British Association to arrange for the collection, preservation, and systematic registration of photographs of points of geological interest says that, while the photographs collected during the past two years are less in number than those of the previous period, a greater proportion are of high scientific interest and illustrate features of real geological importance. But considerable work is yet required to be done toward the completion of a scheme for the full illustration of the geological features of the United Kingdom.

A preliminary account was read in the British Association by Dr. Buchan of oceanic circulation as deduced from the Challenger observations. The author was convinced that a thorough knowledge of the subject could only be attained after a study of the prevailing winds, as the currents followed the winds. He then described the circulation of currents in the North Atlantic, and said that these currents were lost at a depth of over five hundred fathoms, below which point the ocean had always a constant temperature at all depths. The same condition was reached at fifteen hundred fathoms in the Pacific Ocean. He went on to trace the course of the warm dense salt water issuing below the surface from the Mediterranean through the Strait of Gibraltar. This, he said, traveled northward, skirting the west coast of Europe, and thus warming the water even to the north of Norway. He considered that the current was sufficiently warm and strong to prevent the entrance of icebergs into the North Sea.

The observations of dust in the air, made eight times a day last year at the top of Ben Nevis, showed well-marked variations in the amounts present at different times of day. Further, it was found that thick, dry fogs contain a large amount of dust, whereas the thin, wet mists contain little or none.

In the course of his paper in the British Association on the Application of Interference Methods to Spectroscopic Measurement, Prof. Michaelson, of America, found that the results seemed to show that every line of the spectrum is compound, though in many cases the two components are very close together, and have very unequal intensities. The red line of oxygen has three distinct components; the red line of hydrogen is an extremely close double, with nearly equal components; and the green line of cadmium has two components, one of which is ten times as intense as the other.

In illustration of results obtained by the Rev. T. J. Smith in inductoscript (writing by induction currents), Mr. R. E. Baynes, in the British Association, caused the spark of an induction coil to be passed from a coin to a photographic plate on which it was placed. The plate was then developed, and showed an image of the coin. On performing the experiment in a vacuum no such result was obtained. The effect could be got with bromide paper as well as with plates.

The American Association voted grants of a hundred dollars each to Prof. Hart, for investigations in chemistry; to Prof. Joseph Jastrow, in psychology; and to the physical table to be located at Naples.

Describing, in the American Association, the Prehistoric Earthworks of Henry County, Ind., Mr. T. B. Redding said that there were in that county ten curiously formed mounds, surrounded by inclosures, and a number of additional ones, though some of them are not so evident as to be noticed by the casual observer. There are also six inclosures in which mounds do not appear. They may have been obliterated. The mounds range from twenty to a hundred and fifty feet in diameter, and the inclosures are from a hundred to two hundred and fifty feet in diameter. Many of the mounds crumble away on being exposed by taking off the turf covering, while others are in a good state of preservation. A number of relics and skeletons were exhibited during the reading of the paper.