Page:Popular Science Monthly Volume 85.djvu/230

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was 30 inches in diameter in 1890 had increased to be 74 inches in 1913. Also, a huge coral which Saville-Ivent called "Porites astræoides" was 19 feet in diameter in 1890 and 22 feet and 9 inches in 1913. On the other hand, a certain gray-green Gonaistrea, which was 8 feet, 2 inches wide in 1890 had not grown during the intervening 23 years. Indeed, Dr. Vaughan's growth experiments upon Florida corals show that perhaps all corals grow to well-defined sizes and then cease to enlarge. However, the corals that did grow at Vivien Point had increased in diameter from 44 to 45 inches in 23 years, or about 1.9 inches per annum.

Thus charts of channels which are only occasionally used, and the