For some weeks past the French War Office has been engaged in conducting experiments with a view to securing reliable communication for military purposes between Paris and the eastern garrison towns by means of wireless telegraphy. Though many difficulties had to be encountered, these were eventually overcome, and after the system had been extended as far as Vardon and Chalons, the important stronghold of Belfort was furnished with apparatus for wireless telegraphy. AccordiHg to the "Electrical Engineer," London, there is now complete and permanent communication between Paris and all the eastern garrisons.

Kerosene, which is used for fuel to a considerable extent in combustion engines, is made from the distillation of crude petroleum. It takes on an average 3 1/2 parts of crude oil to render 1 part of kerosene. The heat of combustion depends, of course, on the composition, but will range between 22,000 and 24,600 British thermal units per pound. The quicker the distillation, the poorer will be the kerosene, although it will be obtained in larger quantities. The burning point of kerosene is between 130 and 140° F., and it will boil anywhere between the limit of 300 and 500° F., giving a vapor density of five times that of air and requiring for its combustion nearly 190 cubic feet of air per pound.

A new method for increasing the density of steel is described in " Stahl und Eisen ". The object is to allow for the escape of the occluded gases in the metal by keeping the upper part of the ingot in a fluid condition until the mass of the ingot has solidified. To accomplish this a burner cap is placed on top of the ingot mould and a gas blast flame is directed downward upon the metal; vent holes at the side of the cap allows the gases to escape. The flame is so proportioned as to keep the upper part of the ingot considerably above the melting point, thereby causing the ingot to solidify progressively upward. The metal can thus follow the contraction in volume, and the gases are free to escape.

What is said to be the largest wind engine in this country is a great Dutch wind mill recently erected on the Ocean Boulevard, San Francisco. The concrete sub-base is 13 feet in diameter, with walls tapering in thickness from 48 inches to 30, and rests upon a concrete foundation 50 feet in diameter and 54 in. deep. The four great arms have each a radius of 51 feet and a wind area of 400 square feet, making 1600 in all. The main shaft, which is 13 inches in diameter and 18 feet long, is elevated 12 degrees above the horizontal on the score of efficiency. The big 24-foot turret which keeps the big wheel always facing the wind. The lowest wind velocity at which the mill will operate is eight miles per hour, at which 5 horse-power is developed; at twenty miles 200 horse-power is obtained. The tips of the long arms always travel more than twice as fast as the wind.

The earliest mention of coal among the ancient authors is by Theophrastus, in his "History of Stone, " wherein he says: "There is a fossil substance called coal which is broken for use; it kindles and burns like wood. It is found in Liguria and in Ellis, in the way to Olympia over the mountains. These coals are used by the smiths." It is very probable that coal as we know it was used by the primeval Britons for metallurgical operations. The Romans were undoubtedly acquainted with coal, for cinders, or coke, was discovered amid the ruins of their iron forges. It was certainly used by them in their pottery furnaces at Con-data, Warrenton, where quarries of wigan cannel coal, and cinders or coke were found, in connection with an extensive collection of pottery, now preserved in the museum of that town.

When solid water becomes liquid, or when liquid water becomes gaseous, a considerable amount of heat is rendered latent. Steam issuing from boiling water is no hotter than the water itself; water formed when ice is melting is no hotter than the ice itself, yet heat is being communicated to the ice and to the water.

There is a huge natural magnet in Upper Burmah, India, covered with great blocks of iron ore, which has a tremendous attraction, rendering compasses and watches useless.