It is well known to meteorologists that the wind vanes as ordinarily placed near the surface do not give a true indication of the wind. Even when the vane is not over a city or town where the air currents near the earth are affected by the direction of the streets, the varying character of the surface in respect to radiation and absorption of heat will modify them. It is therefore for good reasons that vanes are perched up on high flagstaffs fixed on the roofs of buildings. Some of these are more than a hundred feet above the ground, but recent observations in Paris show that this is not enough. Small India-rubber balloons a foot in diameter and with an ascensional force of about one ounce were sent up, and as they rose slowly, at the rate of twelve feet per second, the effect of the air currents upon them could be easily marked. This was found to be very variable at heights of less than one or two hundred metres (300 to 600 feet). The conclusion was that no observations at lower levels were trustworthy. * * * * * THE GREATEST OF RIFLES. In spite of the familiarity with great cannon which the advances in gun construction of late years have produced, the experiments with the 100-ton gun of the Italian government have not failed to awaken general interest and wonder. It fires a 2,000-pound shell, and a charge of 240 pounds of powder is but a portion of what the gun will bear. These light charges have to be used if the penetrative effects of the gun under unfavorable conditions are to be studied, for with its full charge the weapon simply destroys anything that is put before it. Comparative results cannot be obtained when the only effect is complete ruin. It is somewhat remarkable that an over confident iron founder should have chosen this weapon to test once more the value of _cast_ iron for defensive armor. His idea was that armor could be made so hard by chilling the surface that the shot would be broken to pieces upon it, and experiments with a good iron and guns of small calibre had encouraged the hope. But a 2,000-pound shell and 400 pounds of powder in the 100-ton gun proved anew the unfitness of this material for armor plating. The shot had a velocity of 1,494 feet per second, and it smashed through an 8-inch plate of wrought iron, a wood layer, and a 14-inch plate of chilled cast iron. The ruin produced was greater than in any other experiment, the cast iron breaking into fragments. The power of this gun, the greatest rifle ever made, is such that a solid 22-inch plate of the best English wrought iron is completely penetrated by its shot. * * * * * VIENNA BREAD.