 | James Samuelson, William Crookes - Science - 1865 - 874 pages
...spots. These consist of an umbra or central darkness, surrounded by a less dark penumbra. Mr. Dawes has discovered in some spots even a deeper darkness in the centre of the umbra. Now, if it be correct to suppose that spots are cavities, of which the umbra forms the bottom, and the penumbra... | |
 | Chemistry - 1865 - 332 pages
...spots. These consist of an umbra or central darkness, surrounded by a less dark penumbra. Mr. Dawes has discovered in some spots even a deeper darkness in the centre of the umbra. Now, if it be correct to suppose that spots are cavities, of which the umbra forms the bottom and the penumbra... | |
 | Chemistry - 1865 - 640 pages
...ipots. These consist of an umbra or central darkness, surrounded by a" less dark penumbra. Mr. Dawes has discovered in some spots even a deeper darkness in the centre of the umbra. Now, if it be correct to suppose that spots are cavities, of which the umbra forms the bottom and the penumbra... | |
 | Royal Institution of Great Britain - Science - 1866 - 742 pages
..."sun-spots." These consist of an umbra, or central darkness, surrounded by a less dark penumbra. Mr. Dawes has discovered in some spots even a deeper darkness...penumbra which is nearest the visual centre of the disc. Prof. Alex. Wilson, of the University of Glasgow, was the first to remark that spots really behaved... | |
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These consist of an umbra or central darkness, surrounded by a less dark penumbra. Mr. Dawes has discovered in some spots even a deeper darkness in the centre of the umbra. Now, if it be correct to suppose that spots are cavities, of which the umbra forms... 