Although the Zeppelin undoubtedly has been over-rated by the forces to which it is attached, at the same time it must not be under-estimated by its detractors. Larger and more powerful vessels of this type have been, and still are being, constructed, culminating, so far as is known, in the "L-5," which is stated to have a capacity of about 1,000,000 cubic feet, and to possess an average speed of 65 miles per hour.

While it is generally maintained that the Zeppelins will prove formidable in attack, greater reliance is being placed upon the demoralising or terrifying effect which they are able to exercise. Owing to the fact that from 3 to 5 tons of fuel - say 900 to 1,500 gallons of gasoline or petrol - can be carried aboard, giving them a wide radius of action, it is doubtful whether they could travel from Cologne to London and back upon a single fuel charge, since such a raid would entail a journey of about 600 miles. The latest types of this craft are said to possess a high ascensional speed, which offers a distinct protection against aeroplane attack. According to such official information as has been vouchsafed, a Zeppelin, when hard pressed, is able to rise vertically 3,500 feet in about three minutes. This is far in excess of the ascensional speed of even the speediest aeroplane. of course, the penalty for such a factor has to be paid: the loss of gas is appreciable and may lead to the craft's ultimate undoing. At the same time, however, it is able to maintain the superior position as compared with the aeroplane for a considerable period: the upper reaches of the air are its sanctuary.

Nor must the nocturnal activities of the Zeppelin be overlooked. So far as night operations by these vessels are concerned, little has leaked out, so that the possibilities of the airship in this direction are still somewhat hypothetical. The fact remains, however, that it is night movements which perhaps are the most to be dreaded by the enemy. According to official German sources of information the latest types of Zeppelins are engined by "noiseless" motors. There is nothing remarkable in this feature, since the modern motor-car virtually answers to this description, although in this instance quietness is obtained for the most part by recourse to the sleeve-valve engine. Still, the ordinary Otto-cycle internal combustion engine can be rendered almost silent by the utilisation of adequate muffling devices, which, in the Zeppelin, are more possible of incorporation than in the aeroplane, because the extra weight imposed by this acquisition is a minor consideration in comparison with the lifting power of the vessel.

Night operations, however, have not proved eminently successful. The very darkness which protects the aerial prowler also serves a similar purpose in connection with its prey. But aerial operations under the cover of darkness are guided not so much by the glare of lights from below as betrayal by sound. The difference between villages and cities may be distinguished from aloft, say at 1,500 to 3,000 feet, by the hum which life and movement emit, and this is the best guide to the aerial scout or battleship. The German authorities have made a special study of this peculiar problem, and have conducted innumerable tests upon the darkest nights, when even the sheen of the moon has been unavailable, for the express purpose of training the aerial navigators to discover their position from the different sounds reaching them from below. In other words, the corsair in the skies depends more upon compass and sound than upon compass and vision when operating after dark. The searchlights with which the Zeppelins are equipped are provided merely for illuminating a supposed position. They are not brought into service until the navigator concludes that he has arrived above the desired point: the ray of light which is then projected is merely to assist the crew in the discharge of the missiles of destruction.

The Zeppelin, however, owing to its speed, both in the horizontal and vertical planes, is essentially a unit for daylight operations. The other airships which Germany possesses, and which for the most part are of the non-rigid type, are condemned to daylight operations from the character of their design. Owing to their low speeds they may be dismissed as impossible aerial vessels for hazardous work and are not regarded by the German authorities as all-round airships of war.

Craft of the air are judged in Germany from the one standard only. This may be a Teutonic failing, but it is quite in keeping with the Teutonic spirit of militarism. Commercialism is a secondary factor. To the German Emperor an airship is much what a new manufacturing process or machine is to the American. Whereas the latter asks, "How much will it save me on the dollar?" to the War Lord of Germany - and an airship notwithstanding its other recommendatory features is judged solely from this standpoint - the question is "What are its military qualifications?"

When the semi-rigid airship "V-I" was brought before the notice of the German military department the pressing point concerning its military recommendations arose at once. The inventor had foreseen this issue and was optimistic. Thereupon the authorities asked if the inventor were prepared to justify his claims. The retort was positive. Forthwith the Junkers decided to submit it to the test.