摘要

Kristian Birkeland and his terrella experiment.

"The Figure shows the whole arrangement with the new vacuum-box of 320 litres. Floor and ceiling are here made of 12 mm. steel plates, the pillars between are of bronze, and the sheets of plate-glass at the sides are 30 mm. in thickness. The experiment shows the "zodiacal-light ring". It requires little magnetising of the globe (11.3 cm. in diameter), but a great discharge-current (up to 100 milliamperes)."

Sourced from the book, The Norwegian Aurora Polaris Expedition 1902-1903, Volume 1: On the Cause of Magnetic Storms and The Origin of Terrestrial Magnetism, Section 2. Chapter VI: p.667 (published in 1913), By Kristian Birkeland (1867-1917) also on the Web at [url=http://www.catastrophism.com/texts/birkeland/]

Source: english wikipedia, original upload 5 June 2005 by Iantresman en:Image:Birkeland-terrella.jpg

	这个媒体文件在美国属于公有领域。这适用于版权过期的美国作品，通常因为其首次出版于1929年1月1日之前，或即便当天或以后出版，其并未包含版权通告或获得版权回溯。查看这个页面可以获取到更多的解释。
	这个图片在美国以外可能尚未处于公有领域；尤其在对美国作品不适用较短期限法则的国家和地区，如加拿大、中国大陆（不含香港及澳门）、德国、墨西哥和瑞士。创作者和发表年份是关键信息，因此必须提供。参见维基百科:公有领域及维基百科:版权信息以获取更多细节。