Democratic Sentinel, Volume 9, Number 51, Rensselaer, Jasper County, 22 January 1886 — POPULAR SCIENCE. [ARTICLE]

POPULAR SCIENCE.

li is said that the medical examiners of the boys who were candidates for the place of appreuti os in the navy found that nearly all suffered from heart trouble or imperfect eyesight, caused by smoking cigarettes. „ K:.; John* Lrr.mwK, in some observations on the intelligence of the dog, -ug rests that dogs might bo made to under* and by means of a system like that u. ed for deaf mutes. He had a dog which would pick out a card containing a request for food or drink. R. F, Fiuswelt., in a paper read before the Chemical Society, London, says that the results of his personal experience with toughened glass, during a period of eleven months, have caused him to regard that substance, when formed into laboratory utensils, as a complete failure. In insects the sex of an individual is not determined until toward the oud of the larval stage. Entomologists who rear moths and butlertiies contend that when the food supply is scanty the majority of perfoot insects produced are males, while if food is superabundant females preponderate. The painstaking researches of Prof. S. P. Langley have caused him to reject Lord l Osse’s asssnmption that the temperature of the moon’s surface rises to 20.) or 300 degs. F. during tho lunar day, and falls about as far below zero in the lunar night. Prof. Langley finds that the temperature can never rise above a point where everything, perhaps ovon the gases, is frozen solid. M. Levasskvk computes that at the commencement of the eighteenth contury there were 9,500,000 Europeans who lived in various lands outside of Europe. Including these people, the whole population of Europe was 185,590,000. 'At present there are 82,009,000 living in other countries, but the population of Europe continues to increase rapidly, and is now 335,000,000. That is, it has nearly doubled Bineo 1700, while tho emigration from it is now nine times as largo as it was at that time. Evidently the lifo philosophic tends to longevity. There are at present, at the various German universities, no fewer than 157 professors between the ages of seventy and ninety. Of these, 122 deliver tlioir lectures as usual, seven of them being more than eightyfive years of age. The oldest is the veteran Von Ranke, the historian, who is now in his ninetieth year, but is not considered fully equal in vigor, memory, and other matters to Prof. Elveniuh, who is thirty-nine days his junior. After all, it is not roinarkable that a professor should live to a good old age. He lias a secured income and congenial pursuits. He ought to be devoid of the unworthy passions that shorten existence, and to lead a life as placid as that of the gods of Epicurus. But Germany, in spite of the figures we have quoted, cannot show a professor equal to M. Chevrouil, of Paris, who still lectures, still writes, still conducts experiments in chemistry, still walks every day from his house to his laboratory, and will, if ho lives, be 100 years of ago in August, 1880.