JF Ptak Science Books Part of the series on the History of Lines
Seems like an easy topic--it isn't.
Perhaps there are no more "basic" a collection of lines than those made in sand, either at the beach, in water, or in the desert, created by water or wind, changes to the surface of a mass at the intefave of the fluid. They seem to be about as basic as things can be, line-wise, or at least in lines that can be found in nature and not made by humans. These lines are called "ripples", and ripples have numerous names and classifications. Not many, though, in 1883, where I found this lovely article in Nature by Charles Darwin's son, George. (This is a shorter version of a 25-page earlier paper "On the Formation of Ripple-mark in Sand," In the Proceedings of the Royal Society, November 22, 1883, vol. 36.)
It is a wonderful thing this thinking on the movement of sand, and dirt, these wave-formed ripples, created in forms straight, sinuous, cantenary, lingoid. It also is followed closely in by George Darwin's article on the formation of mudballs (volume 27, page 507). Who could not but read an article like that?
Also it brought to mind his father's Power and the Movement in Plants, and specifically a letter to the editor of Nature in the April 28, 1881 issue of Nature, "The Movements of Leaves" in response to bright light...)
Notes:
In a fabulous paper, "The Origin and Growth of Ripple-mark." published in the Proceedings of the Royal Society of London A84: 285 (1910) , W. E. Ayrton introduces the topic with a poetic few words and describes the Darwin paper:
"1. Starting of the First Ripple.—To the first question as to the origin of ripplemark - fundamental as it is - I could, for some time, find no satisfactory answer, either in nature or in books. Even the deeply interesting paper in which Prof. George Darwin described the vortices he had discovered in the water oscillating over ripplemark touched but lightly on this point. Prof. Darwin said: "When a small quantity of sand is sprinkled [in a glass trough] and the rocking begins, the sand dances backwards and forwards on the bottom, the grain rolling as they go."
"Very shortly the sand begins to aggregate into irregular little flocculent masses, the appearance being something like that of curdling milk. The position of the masses is, I believe, solely determined by the friction of the sand on the bottom."
And again: "We now revert to the initiation of ripplemark.
"If the surface be very even, as when sand is sprinkled on glass, when a uniform oscillation of considerable amplitude be established, the sand is carried backwards and forwards and some of the particles stick in places of greater friction. A soon as there is any superficial inequality, it is probable that a vortex is set up in the lee of the inequality which tend to establish a dune there."
And so on. read the Ayrton paper here: http://cwp.library.ucla.edu/articles/ayrton/Ayrton_ripple/ripple.html
Comments