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absorption Afrikaner America amplitude Aragon army atoms Barcelona became British Cape Cape colony Castile Catalan Catalonia central centre century chief choanocytes church civil coast coastal colony colour consists cord Cortes developed diaphragm eastern effect electrical electrons energy excited force French frequency important Inca increased industries intensity islands king known land Laplace's equation later light lines London Madrid means measured ment method motion native northern observed officers operations organization period plate political population prism produced province radiation reflex region resonance result river slit sound sound-waves South Africa southern Spain Spanish Sparta species spectra spectral lines spectrum spicules spiders spinal Spinoza Spitsbergen sponges sq.mi staff stars surface temperature theory tion town Transvaal tube Union United velocity vibrations Visigothic wave lengths