July | 2015 | ritstaalman

The ancient peoples of Babylon and Egypt have presented us with many valuable scientific and technical innovations. In the fields of arithmetic, geometry and astronomy they made major contributions and in the art of erecting barehanded buildings from huge stone blocks they are unsurpassed to this day. But as far as I know they did not get involved in the theory of gases, nor did they build machines to conquer the sky.

The history of the balloon starts with Greece, where Archimedes (287-212 B.C.) formulated the principles of sinking, rising and floating and Hero (20? A.D.) invented the plunger type water pump. In our own seventeenth century there was Torricelli (1608-1647), who demonstrated the phenomenon of a vacuum by upending a long glass tube filled with mercury and Von Guericke (1602-1686) who adapted Hero’s pump to pump air. In this way he could evacuate his famous Magdeburger Half Spheres and demonstrate the surprising force exerted by the pressure of the column of air above us.

One result of all these experiments with vacuum was that the idea that air had weight became generally accepted.
Magdeburger balls emptied of their inside air were somewhat lighter than air-filled ones. Giovanni Alfonso Borelli (1608-1679, see my previous post), Italian physiologist, mathematician and friend of Galileo, speculated that if one would make very light spheres, for instance out of very thin copper plate and draw all the air from their insides, they would float in the air according to the law of Archimedes. Unfortunately spheres formed out of very thin plate would not be able to withstand the atmospheric pressure from outside and would be flattened by it.

Undaunted by considerations like these the Jesuit father Lana de Terzi (1631-1687), who longed to go to heaven, made the same fatal flaw in his thinking. In his book ‘Prodromo Overo Saggio de Alcune’ of 1670 he describes a true ship of the air, an open gondola lifted by four copper spheres of almost 25 feet diameter that have no air inside. The ship is drawn forward by a span of twelve geese. De Lana was probably the first to be concerned that this invention, like all other man made instruments, could be misused for war. An airship such as this would make war even more brutal and horrifying than de Lana had experienced in his own lifetime. He therefore concluded that God would prevent the construction of this sort weapons. He certainly was he a naive optimist.

Of course his idea of the twelve geese was endearing. In flight it must have looked somewhat like the picture hereafter, which shows the Canadian Joseph Duff flying southward with a flock of cranes that have as much trust in their pilot as de Lana had in his god.

Do read:

“Operation Migration” founder still flying to save endangered birds; whooping cranes not Canada geese.

On Sunday July 5^th, while enjoying my time at the beach, Daniel Boria, age 26, was floating over the Calgary stampede grounds carried aloft by 110 helium filled balloons while sitting in a lawn chair.
Our fascination with balloons goes back a long time, to Francisco Lana-Terzi [1631-1687] or maybe even earlier, to Giovanni Alfonso Borelli as decribed by that famous science (fiction) writer Isaac Asimov [1920-1992]:[1]

BORELLI, Giovanni Alfonso
Italian mathematician and physiologist
Born: Naples, June 28, 1608
Died: Rome, December 31, 1679

“Borelli was a professor of mathematics and a friend of Galileo. His life, though not characterized by the controversies of his great friend, was not entirely smooth. In 1674 he had to leave Messina, the Sicilian city in which he was then teaching, and retire to Rome, where he remained under the protection of Christina, former queen of Sweden. (This was the queen whose eccentric habits had brought on the death of Descartes [1596-1650]. She abdicted in 1654 and was received into the Roman Catholic Church the following year, after which she settled in Rome.)

Borelli corrected some of Galileo’s overconservation. Galileo [1564-1642] had neglected Kepler’s [1571-1630] elliptical orbits, but now Horrocks [1618-1641] had extended them even to the moon, and Borelli rescued the ellipses, publicizing and popularizing them.

He tried to extend the vague notions of Galileo and Kepler concerning the attractive forces between the sun and the planets, but was not successful. He tried also to account for the motion of Jupiter’s satellites by postulating an attractive force for Jupiter as well as for the sun. In this he (and Horrocks also at about this time) made a tentative step in the direction of universal gravitation, but the theory had to wait a generation for Newton [1642-1726].

Borelli suggested (under pseudonym) that comets travelled in parabolic orbits, passing through the solar system once and never returning. (The parabola, like the ellipse, was first studied by Apollonius [261-190 BC]. A parabola is an open curve something like a hairpin.) Any body following a parabolic path would approach the sun from infinite space, round it, and recede forever. Such an orbit would explain the erratic behavior of comets, without completely disrupting the orderliness of the universe.

Borelli understood the principle of the balloon, pointing out that a hollow copper sphere would be buoyant when evacuated, if it were thin enough, but that it would then collapse under air pressure.
It did not occur to him that collapse could be avoided if a lighter-than-air gas were used to fill the sphere as, in essence, the Montgolfier brothers [1740-1810 and 1745-1799] were to do a century and a half later.”
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[1] Isac Asimov: Biographical Encoclopedia of Science and Technology (chronically ordered); 805 p. Avon Books, 1976

airplane construction interbellum – like Rohrbach and many other pioneers

ritstaalman

Monthly Archives: July 2015

1670: METAL SPHERES IN THE SKY

July 2015: CALGARY LAWN CHAIR BALLOONS

airplane construction interbellum – like Rohrbach and many other pioneers