Page:Popular Science Monthly Volume 8.djvu/784

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764
THE POPULAR SCIENCE MONTHLY.

The velocity with which storms advance is further considered in this paper. It was previously stated that the rate might vary from a stationary condition for many hours, or several days, to the extreme velocity of 1,200 miles in a day, or even 57.5 miles an hour.

By an examination of European maps it appears that storms over Europe travel at an average rate of 26.7 miles per hour, and it was found from examination of American maps that they move at about the same rate in this country. But over the Atlantic Ocean the movement is only 19.6 miles, showing that the velocity is less over the ocean than over the land.

This proves that the progress of a storm is not merely a drifting of the atmosphere; for, observes the professor, it seems probable that the average progress of the atmosphere in an easterly direction is as rapid over the Atlantic Ocean as it is over North America.

 

How Rats and Mice use their Tails.—To test the correctness of the popular belief that rats and mice use their tails for feeding purposes, when the food to be eaten is contained in vessels too narrow to admit the entire body of the animal, a writer in Nature made the following experiments: Into a couple of preserve-bottles with narrow necks he put as much semi-liquid fruit-jelly as filled them within three inches of the top. The bottles were then covered with bladder, and set in a place frequented by rats. Next morning the covering of each bottle had a small hole gnawed in it, and the level of the jelly was lowered to an extent about equal to the length of a rat's tail if inserted in the hole. The next experiment was still more decisive. The bottles were refilled to the extent of half an inch above the level left by the rats, a disk of moist paper laid upon the surface, and the bottles covered as before. The bottles were now laid aside in a place unfrequented by rats, until a good crop of mould had grown upon one of the moistened disks of paper. This bottle was then transferred to the place infested by the rats. Next morning the bladder had again been eaten through at one edge, and upon the mould were numerous and distinct tracings of the rats' tails, evidently caused by the animals sweeping their tails about in the endeavor to find a hole in the paper.

 

Experiments in Beet-Culture.—In the course of their experiments on beet-culture, Dehérain and Fremy planted some beets in absolutely sterile soils, to which were added from time to time such substances as were thought to be essential for the development of the plant. It was found that the beets continued in the rudimentary state when they received in such soils only distilled water; they increased slightly in weight when common water took the place of distilled; their development was greater still when the water contained soluble phosphates, or salts of potash; but yet the roots never attained the weight of 100 grammes. When for these mineral substances were substituted ammoniacal salts or nitrates, the yield was much better. Normal beets, however, cannot be grown unless to these nitrogenous fertilizers are added phosphates and potash salts. It is worthy of note that, when the beet finds in the soil nitrogen, phosphorus, potash, and lime, it develops as well as in a soil containing humus. To establish this point Messrs. Dehérain and Fremy compared the produce of two such soils, and found that the beets grown in sterile soil were heavier than those grown in rich soil.

On examining the beets grown in plots in the experimental garden of the museum, the authors found them to be very poor in sugar, though the soil was very rich. From this it follows that deficiency of sugar in the beet is not due to exhaustion of the soil. In seeking the true cause, it occurred to Messrs. Dehérain and Fremy to ascertain how much nitrogen the beets contained, and found it to be very large. Hence it appeared that a soil rich in nitrogeneous matters is unfavorable to the production of sugar. This conclusion was confirmed by sundry analyses of beets grown at the museum, at the school of Grignon, and in the departments of Aisne, Nord, and Eure. All the results positively confirm the observations made by the authors, and their conclusion is that, if beets are now less rich in sugar than formerly in those departments which have long produced them, that fact is not owing to the exhaustion of the soil and its deprivation