II. EARLY EXPERIMENTS

Continued from page 9......
Having thus detailed the method of exhausting air from a vessel, Lana goes on to assume that any large vessel can be entirely exhausted of nearly all the air contained therein. Then he takes Euclid's proposition to the effect that the superficial area of globes increases in the proportion of the square of the diameter, whilst the volume increases in the proportion of the cube of the same diameter, and he considers that if one only constructs the globe of thin metal, of sufficient size, and exhausts the air in the manner that he suggests, such a globe will be so far lighter than the surrounding atmosphere that it will not only rise, but will be capable of lifting weights. Here is Lana's own way of putting it:--

'But so that it may be enabled to raise heavier weights and to lift men in the air, let us take double the quantity of copper, 1,232 square feet, equal to 308 lbs. of copper; with this double quantity of copper we could construct a vessel of not only double the capacity, but of four times the capacity of the first, for the reason shown by my fourth supposition. Consequently the air contained in such a vessel will be 718 lbs. 4 2/3 ounces, so that if the air be drawn out of the vessel it will be 410 lbs. 4 2/3 ounces lighter than the same volume of air, and, consequently, will be enabled to lift three men, or at least two, should they weigh more than eight pesi each.

It is thus manifest that the larger the ball or vessel is made, the thicker and more solid can the sheets of copper be made, because, although the weight will increase, the capacity of the vessel will increase to a greater extent and with it the weight of the air therein, so that it will always be capable to lift a heavier weight. From this it can be easily seen how it is possible to construct a machine which, fashioned like unto a ship, will float on the air.'

With four globes of these dimensions Lana proposed to make an aerial ship of the fashion shown in his quaint illustration. He is careful to point out a method by which the supporting globes for the aerial ship may be entirely emptied of air; this is to be done by connecting to each globe a tube of copper which is 'at least a length of 47 modern Roman palm).' A small tap is to close this tube at the end nearest the globe, and then vessel and tube are to be filled with water, after which the tube is to be immersed in water and the tap opened, allowing the water to run out of the vessel, while no air enters. The tap is then closed before the lower end of the tube is removed from the water, leaving no air at all in the globe or sphere. Propulsion of this airship was to be accomplished by means of sails, and also by oars.

Aviation Videos: Danger Flight (1939) [DVD] A Tailspin Tommy Movie Based On t...
Tailspin Tommy is the lovable stunt pilot born from twenties comic strips who became a feature film franchise. Here in Danger Flight, Tommy returns to straighten out some juvenile delinquents. Featuring some beautiful post World War I style aviation, Tailspin Tommy teaches the children about the wonders of flight and gives them wholesome hobbies. This includes some great looks at vintage model airplanes. But disaster strikes when Tommys plane wrecks! Danger Flight is quality family entertainment with a beloved American character.

Director: Howard Bretherton
DVD: Year: 1939, Run time: 59:55, Director: Howard Bretherton, Starring: John Trent, Marjorie Reynolds, Milburn Stone, Jason Robards Sr., Tommy Baker, Dennis Moore, Julius Tannen, Eddie Parker
Company: Quality Information Publishers, Inc. (2008)
List Price: $9.99
Amazon Price: $9.99

PART I: THE EVOLUTION OF THE AEROPLANE

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