Even the best war balloons of a few years ago were at the mercy of the winds. It is not so with the blimp. Barring storms, it is able to navigate the air as it wishes. It can rise safely to an altitude of a mile and a half. To furnish fuel for its engine of 100 horsepower it carries, in two tanks, 100 gallons of gasoline. DESCRIPTION OF THE "BLIMP." In effect, the blimp is a combination of balloon and aeroplane. Like the latter, it is provided with "skids" (resembling sled runners and made of ash wood), or sometimes with bicycle wheels, for safe landing on terra firma. When designed for sea scouting, floats--cylinders of waterproof fabric stuffed with vegetable fibre--are attached to the skids, or to the wheels, so that the airship, in calm weather, may be able to rest, like a sea bird, on the waves, if desired. The blimp's balloon envelope must contain two smaller balloons, together holding 19,250 feet of hydrogen gas. The idea, of course, is that if anything happens to the major balloon--puncturing by gunfire or by other mishap--the "balloonets" inside of it will keep the machine afloat. The wingless aeroplane is suspended from the balloon by cables of galvanized wire. There is a special arrangement by which the "pilot"--the man who steers and operates the airship--can at any time measure the pressure of hydrogen in the balloon, thus knowing what he has to count on in the way of carrying power. The front part of the blimp's car is occupied by the engine and radiator, behind which is a bulkhead of sheet steel. In the rear of this bulkhead sits the pilot, and behind him the "observer," who makes sketches and takes notes of anything important that he sees. Behind the observer are the tanks for fuel oil and 300 gallons of water ballast. The body of the car is covered with aeroplane linen, save for the engine, which is sheathed with sheet aluminum. In order to hold whatever position in the air may be desired, the blimp is equipped with two horizontal fins and three vertical fins. Not every blimp, that is to say, but the pattern approved and required of contractors by the Navy Department. These fins are made of wood and light steel tubing, reinforced with wire, covered with aeroplane linen rubber painted and finished with varnish. THE "BLIMP" WELL EQUIPPED. There are also two horizontal rudders and two vertical rudders, for steering up and down or sidewise. They work on ball bearings. A blimp, one should understand, is a fish in the ocean of air, a swimmer--just as the aeroplane is a flyer, like the bird. The blimp's "car" carries an electric storage battery to furnish lights. The same battery energizes a searchlight for night scouting. A wireless apparatus, for transmitting information to the shore station, is part of the equipment.