The basic shape of the North American continent on a map is best described as which?
Hearing the shape of a drum Lester R. Ford Award in 1967 and the Chauvenet Prize in 1968. The frequencies at which a drumhead can vibrate depends on its shape. The Helmholtz equation calculates the frequencies if the shape is known. These frequencies are the eigenvalues of the Laplacian in the space. A central question is whether the shape can be predicted if the frequencies are known; for example a circle-shaped triangle can be recognized in this way. Kac did not know whether it was possible for two different shapes to yield the same set of frequencies; the question was finally answered by the negative in
A Map of Middle-earth A Map of Middle-earth A Map of Middle-earth is the name of two colour posters by different artists, published in the late 1960s and early 1970s by the American and British publishers of J. R. R. Tolkien's book "The Lord of the Rings". Both posters were based on cartography by J. R. R. Tolkien and Christopher Tolkien to depict the fictional region of Middle-earth. None of these maps cover the whole continent of Middle-earth; instead they only portray the north-western part of the continent, where the story of "The Lord of the Rings" takes place. The earlier poster, signed "BRem"