 | Daniel Bennett St. John Roosa - 1894 - 728 sider
...Dr. Young continues to remark on the evidence of his astigmatism in saying: "When I look at a minute point, such as the image of a candle in a small concave speculum, it appears as a radiated star, as a cross, or as an unequal line, and never as a perfect point, unless... | |
 | Royal Society (Great Britain) - 1801 - 572 sider
...means. But, for direct experiments, Dr. WOLLASTON'S method is exceedingly accurate. When I look at a minute lucid point, such as the image of a candle in a small concave speculum, it appears as a radiated star, as a cross, or as an unequal line, and never as a perfect point, unless... | |
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WOLLASTON'S method is exceedingly accurate. When I look at a minute lucid point, such as the image of a candle in a small concave speculum, it appears as a radiated star, as a cross, or as an unequal line, and never as a perfect point, unless I apply... 