Open main menu

Page:Popular Science Monthly Volume 36.djvu/591

This page has been validated.

tain pieces can not be printed or colored anything but black. If fibers of such cotton are looked at under the microscope after being mordanted, some parts will be seen prepared for coloring, and others where the mordant has not taken hold. Cotton is often badly damaged by poor ginning; the fibers are torn, and millions of short pieces to every bale are broken off, which in spinning fly all over the mill and machinery, and go into the waste instead of being made into yarn. Much has been said about "parallelism" of cotton fibers in the manufactured goods, but, if a bit of one of the best grades of cotton cloth made is examined under the microscope, there is seen to be no such thing as parallelism among the fibers.


Snow-Blindness.—Snow-blindness, according to Dr. Berlin, of Nordenskiöld's Expedition to Greenland of 1883, is met with as far north as any arctic expedition has penetrated, but is unknown, except sporadically in high mountains, south of certain degrees of latitude. It follows the sinuosities of the isothermal lines. In the arctic regions it breaks out usually in the spring-time, but also occurs in summer wherever snow remains. It appears during snowstorms and fogs, as well as when the sun is shining. The prominent symptom is an intense burning pain in the eyes, beginning with a prickling sensation as if produced by a foreign body, with increased secretion of tears, photophobia, and blepharospasm. The visual power is not diminished, but the field is narrowed. Most cases will get well at the end of two or three days, if the patient guards himself against the exciting causes; or the disease may, exceptionally, become a serious matter. It is not a dazzling caused by the snow, for dazzling does not produce its effects, and it does not prevail everywhere that there are snow and sunlight; nor can it be explained by the fact of the rarefaction of the air. It is probably a result of the low temperature and the want of humidity in the air which characterize the places where it prevails. As it is the humidity of the air which principally absorbs the radiant heat, the caloric rays of the sun must, in those localities, manifest an intensity of action far above the common. Observation has shown that this is the case, for on high mountains and in the arctic regions exposure to the sun's rays produces on the bare skin an excessively painful dermatitis, which the radiant heat reflected by the snow very much aggravates. The effects of exposure to the sun appear to be most severe in spring-time. The eyes are affected simultaneously with the skin or somewhat previously. The ordinary treatment of snow-blindness consists in the use of spectacles of dark-colored glass, with opiates to relieve the pain. Blackening of the nose has been found by several travelers to be an effective remedy.


The Great Hall of the Mammoth Cave.—Some important new discoveries in the Mammoth Cave were described by the Rev. Dr. H. C. Hovey at the meeting of the American Association. They are connected with the arrangement of the cave passages in tiers and the great pits or domes. Following the guide across a treacherous chasm known as the covered pit, the author found a series of these chasms exceeding in size any that had ever been discovered before. He afterward visited the pits with a photographer, Mr. Ben Hains, and means for taking photographs. As measured from above, they varied from forty-seven to one hundred and thirty-five feet in depth. With much difficulty and risk he succeeded in reaching the bottom of Charybdis, the deepest of the pits, and there discovered, by the aid of chemical fires, that the whole series of pits, eight in all, were joined at the bottom into one magnificent hall several hundred feet long. This hall was traversed from end to end. Dr. Hovey proposes to name it Harrison's Hall, after the President of the United States.



A bacterial disease of carnations was described by Prof. J. C. Arthur at the meeting of the American Association. It is revealed by the presence in the leaves of transparent dots that can be seen only by transmitted light. These spots increase and coalesce, and finally kill the tissues, when the leaves dry up and the plant gradually dies. The transparent spots are found, under the microscope, to be due to the enlargement of the cells with bacteria.

When the governor of a province in Madagascar wishes to issue a proclamation,