Newcomb, Simon, 1835-1909 · New York, Harper & brothers · leaf 281
24<J THE SOLAR SPOTS AND ROTATION. hibited the motion jnst described, and it was thence inferred that the sun rotated on his axis in about 25 days. The astronomers of the seventeenth and eighteenth centuries used a method of observing the sun which will often be found convenient for seeing the… … Fig. 65.— Man holding telescope, to show sun on screen. it at the sun. To save the eyes, the right direction may be found by holding a piece of paper closely in front of the eye- piece : when the sun shines through the telescope on this pa- per, the pointing is nearly right. The telescope should be…
Astronomy
Internet Archive · Wellesley College Library · Public domain (published before 1931). Free to use for anything.
