The Origin and History of Colver and Roberts Variometers
P. R. Gazis
SETI Institute, NASA Ames Research Center, Moffett Field, California
Abstract.Variometers are used to measure rates of climb and descent. Along with altimeters, they constitute one of the most basic instruments used for hang gliding and other forms of soaring flight. The proliferation of modern microprocessor-based variometers has tended to obscure the early history of these instruments. In this paper, the origin and history of two primitive variometers, the Colver and Roberts, is discussed in detail.
Colvers were the first variometers to appear on Earth. Primitive Colvers have been identified in fossil strata immediately above the iridium layer that marks the end of the Cretacious era and the extinction of the dinosaurs. It is generally believed that the ancestors of the Colver evolved sometime during the Jurassic and were used by pterodactyls to find lift. Some paleontologists believe that Colvers evolved even earlier, during the Carboniferous era, and were used by soaring insects.
In appearance, Colvers were heavy lumbering boxes contained in a dull aluminum carapace. (Since aluminum does not fossilize readily, this is responsible for the ambiguity of the fossil record). Their diet consisted of AA batteries, the remains of which have been identified inside the stomachs of better-preserved specimins. The Colvers became extinct shortly after the onset of the Holocene era, so little is known about their habits. It was once believed that they were cold-blooded and similar to modern reptiles, but a new generation of paleontologists, lead by Robert Bakker, has suggested that Colvers were warm-blooded active variometers, capable of sophisticated behavior comparable to that of modern flight instruments.
While not as ancient as the Colvers, the origin of Roberts variometers is still rooted in antiquity. Archeaological evidence such as tomb carvings suggests that the use of Roberts variometers was known to the early civilizations of the Middle East. They figure prominently in late Summerian versions of the legend of Gilgamesh, in which the ancestors of mankind escape the wrath of the gods by thermaling up over what must be the first mythological account of a universal deluge. (The legend of Gilgamesh antedates both Greek mythology and the Old Testamant by almost 2000 years).
Early Roberts variometers were fashioned from clay, flint, and bronze, but their internal design has changed markedly with the advent of iron, steel, vacuum tubes, plastic, aluminum, transistors, and most recently, the invention of integrated circuts. Thus, while a modern Roberts variometer may differ little in appearance from its prehistoric ancestors (variometers receovered from Egyptian tombs in the Valley of Kings have the same distinctive 'breadpan' shape as their modern counterparts) it is considerably more reliable and accurate.
The art of Roberts manufacture has endured almost unchanged for thousands of years. It has survived barbarian invasions, religious persecution, and the rise and fall of countless civilizations, but now it is threatened by the changing tastes of the modern world. New designs based on microprocessors, pressure transducers, and digital electronics -- slower, less effective, but smaller and more attractively packaged than the Roberts -- have become fashionable. These new designs have entirely supplanted the older technology in the advanced nations of Europe and Asia, and Roberts variometers are now found only in formerly developed countries such as Santa Barbara and Sunnyvale.
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