New York, February, 1885. * * * * * ORIGIN OF THUNDERSTORMS. At the recent congress of German medical men and physicists, Dr. S. Hoppe, of Hamburg, read a paper in which he sought to show that the electricity of thunderstorms is generated by the friction of vapor particles generated by the evaporation of water. This opinion was strengthened by several experiments in which compressed cold air was allowed to rush into a copper vessel containing warm moist air, thus generating a large amount of electricity. He concludes that the rise of a column of warm moist air into the colder atmosphere above will be followed by a thunderstorm if it acquires sufficient velocity to prevent neutralization of the electricity generated by the friction of the air. Hence, in his opinion, open districts denuded of forests are more liable to thunderstorms than wooded regions, where the trees forbid the rise of humid air currents. * * * * * IMPROVISED TOYS. Do our readers remember all those ingenious toys which our mothers and sisters improvised in order to amuse us? We took a walk into the country, and our eldest sister or our mother picked a wild poppy, turned its red petals back and encircled them with a thread, and stuck a sprig of grass into the seed vessel to represent a headdress of feathers. Here was a fresh and pretty doll (Fig. 1). Another day it was the season of lilacs. The children gathered branches by the armful, and from these the mother picked off the flowers and strung them one by one with a needle. Here was a bracelet or a necklace. An acorn was picked up in the woods, the mother carved it with a pen-knife, and behold a basket. From a nutshell she made a boat, and from a green almond a rabbit. Sometimes she carved the rabbit's ears out of the almond itself, but in most cases they were made from a pretty rose-colored radish. [Illustration: FIG. 1.--Doll made of a Wild Poppy.] Do you remember the cork from which, by the aid of a few long needles for bars, an ingenious fly-cage was formed? And the castle of cards, four, five, and eight stories high? And then those famous card tents in a row, that fell one after another when the first one in the line was overturned? [Illustration: FIG. 2.--Hygrometric Doll; its Dress Colored with Chloride of Cobalt.] How we passed the evenings with our eyes fixed upon our mothers, who patiently, with their skillful scissors, cut horses and dogs out of old white, red, and blue cards! And how many plays, without costing a cent, served to amuse the children by exercising their ingenuity! The mother marked at hazard five dots upon a sheet of paper. The question was to draw a man, one of the dots showing the place of the head and the other four the feet and hands. [Illustration: FIG. 3.--Old Man made of Lobster's Claws.]