(Roughly) Daily

Posts Tagged ‘continental drift

“South America must have lain alongside Africa and formed a unified block which was split in two in the Cretaceous; the two parts must then have become increasingly separated over a period of millions of years like pieces of a cracked ice floe in water”*…

Earth, 600 million years ago. The Ediacaran Period; life is evolving in the sea, and multicellular life is just beginning to emerge.

From the good folks who brought you Dinosaur Pictures, a chance to watch continental drift at work– a marvelous interactive model of the earth that you can view from the present to 600 million years ago: Ancient Earth.

* Arthur Wegener

###

As we marvel at the evolving reality of nature, we might marvel as well at the laws that govern it: it was on this date in 1686, the publication of Newton’s Principia (the Philosophiae Naturalis Principia Mathematicawas arranged in London at the Royal Society. The minutes of the meeting record that the astronomer Edmond Halley would “undertake the business of looking after it and printing it at his own charge.”

Title page of the first edition

source

 

Written by LW

June 2, 2018 at 1:01 am

“It is not down in any map; true places never are”*…

Still, maps hold us in thrall.  Consider, for example, this exquisite piece created around 1715 by Johann Baptist Homann, a German mapmaker working in Nuremberg. It measures 2 ¾ inches in diameter.

This particular pocket globe came in four pieces that nest inside each other like matryoshka dolls. The outside case, made of leather and featuring an S-shaped hook that secured the two pieces together, is lined with concave representations of a celestial map, showing constellations as seen from the earth. (Celestial globes were among the earliest globes produced, and were once commonly sold alongside their terrestrial cousins.)

Inside, the terrestrial globe (on which California is depicted as an island, a common misconception of the time) is hollow. Split into two parts, it reveals an armillary sphere: a type of skeleton celestial globe that represents the movement of heavenly bodies through circles. This armillary sphere has a band around it that’s illustrated with zodiacal symbols.

Katie Taylor, of the Whipple Museum of the History of Science in the U.K., writes that pocket globes could have served as “status symbols for wealthy gentlemen,” or functioned as educational tools for children. Homann made no other globes, specializing instead in maps and atlases; he might have sold this pocket version as a trinket…

The globe is featured in Sylvia Sumira’s Globes: 400 Years of Exploration, Navigation, and Power.  Read more in “An Itsy-Bitsy Early 18th-Century Pocket Globe” at Rebecca Onion’s essential The Vault.

* Herman Melville

###

As we plot our courses, we might spare a thought for Samuel Warren Carey; he died on this date in 2002.  As a geology graduate student in Australia, he read a translation of Alfred Wegener‘s  The Origin of Continents and Oceans, the book largely responsible for introducing the concept of continental drift to the English-speaking world; as a result, he became an early advocate of Wegener’s theory.  Carey’s plate tectonics reconstructions led him to develop the Expanding Earth hypothesis– a theory now largely rejected by the scientific community, but one that generated research and debate that helped advance the field of tectonics materially.

 source

Written by LW

March 20, 2014 at 1:01 am

%d bloggers like this: