Another advantage of lighter-than-air craft is that whereas the restricted space on board an aëroplane leaves little for comfort and convenience, a large rigid airship can easily provide first-rate living, sleeping and dining quarters, besides room for the passengers to take exercise by walking along the length of the inside keel, or on the shelter deck. In a saloon at the top of the vessel no noise from the engines would be heard, as must be the case in whatever quarters could be provided on a passenger aëroplane. Yet another point in favor of the airship as a medium for trans-ocean flight is its greater safety. An aëroplane is entirely dependent for sustentation in the air on the proper working of all its motors. Should two motors--in some cases even one--break down, the result would be a forced descent into the water, with the possibility of total loss on a rough sea, even though the craft be a solid flying boat. In the case of an airship the only result of the failure of any of the motors is reduction of speed. Moreover, a speed of four-fifths of the maximum can still be maintained with half the motors of an airship out of action, so that there is no possibility of a forced descent owing to engine breakdown. The sole result of such a mishap would be to delay the vessel's arrival. Further, it may be noted that an airship's machinery can be so arranged as to be readily accessible for repairs and replacement while on a voyage. As regards comparative speed the heavy type of aëroplane necessary to carry an economical load for long distances would not be capable of much more than eighty-five to ninety miles an hour. The difference between this and the present airship speed of sixty miles an hour would be reduced by the fact that an aëroplane must land at intermediate stations for fuel replenishment. Any slight advantage in speed that such heavier-than-air craft possess will disappear with the future production of larger types of dirigible, capable of cruising speeds varying from seventy-five to ninety miles an hour. For the airship service London-New York direct, the approximate time under normal conditions should be fifty hours. For the aëroplane service London-Ireland-Newfoundland-New York the time would be at least forty-six hours. Perhaps the most convincing argument in favor of airships as against aëroplanes for trans-ocean aviation is that of comparative cost. All air estimates under present conditions must be very approximate; but I put faith in the carefully prepared calculations of experts of my acquaintance. These go to show that, with the equipment likely to be available during the next few years, a regular and effective air service between London and New York will need (again emphasizing the factor of approximation) the following capital and rates: Aëroplane Airship Service[1] Service[2]