 | Smithsonian Institution. Board of Regents - 1856 - 454 páginas
...as a scale of brightness : 1. Faint. 2. Moderate. 3. Bright. 4. Very bright. GENERAL DIRECT1ONS. 1. Make a regular practice of looking for auroras every clear evening, from 8 to 10 o'clock, or later. Record the result, whether there be an aurora or not. ° These instructions... | |
 | Smithsonian Institution, Arnold Guyot - 1858 - 80 páginas
...scale of brightness : — 1. Faint.^ 2. Moderate. 3. Bright. 4. Very bright. GENERAL DIRECTIONS. i 1. Make a regular practice of looking for auroras every clear evening, from 8 to 10 o'clock, or later. Record the result, whether there be an aurora or not. 2. Note the time of... | |
 | United States. Army. Signal Corps - 1882 - 144 páginas
...as a scale of brightness: 1. Faint. 2. Moderate. 3. Bright. 4. Very bright. GENERA1. DIRECTIONS. 1. Make a regular practice of looking for auroras every clear evening, from 8 to 10 o'clock, or later. Secord the result, whether there be an aurora or not. 2. Kote the time of... | |
 | Missouri. State Board of Agriculture - 1891 - 846 páginas
...scale of brightness : (1) faint; (2) moderate; (3) bright; (4) very bright. GENERAL DIRECTIONS. 1. Make a regular practice of looking for auroras every clear evening, from 8 to 10 o'clock or later. Eecord the result, whether there be an aurora or not. 2. Note the time of... | |
 | Thomas Russell - 1892 - 106 páginas
...a scale of brightness: (1) Faint; (2) Moderate; (3) Bright; (4) Very bright. GENERAL DIRECTIONS. 1. Make a regular practice of looking for auroras every clear evening, from 8 to 10 o'clock or later. Record the result, whether there be an aurora or not. 2. Note the time of... | |
 | 1850 - 1174 páginas
...aurora has been seen at all during the night, and if not, whether the state of the sky was favourable or otherwise to observation. Private observers should...precise. Wet or cloudy evenings should be noted. Auroral phienomena may be divided into the following classes :— I. A faint light in the north, without definite... | |
 | 1850 - 582 páginas
...aurora has been seen at all during the night, and if not, whether the state of the sky was favourable or otherwise to observation. Private observers should...whether there has been an aurora or not, together witli the times of observation. The notes may be short, but they should be clear and precise. Wet or... | |
| |
... color. 7. Auroral corona, or a union of beams south of the zenith. 8. Dark clouds accompanying the diffuse light. 9. Sudden appearance of haze over the whole face of the sky. The following may serve as a scale of brightness: (1) Faint; (2) Moderate;... 