Letters on
章节目录
共 33 段- A section of a sphere, by a plane cutting it in any manner,
- Let us first see how the image is formed. This may be done e
- The observatory consisted of a main building, which was squa
- The time of the earth's revolution on its axis, as already e
- The first satisfactory evidence that was obtained of the exa
- Suppose, for example, that the spectator is at the latitude
- Were it not for the power the atmosphere has of dispersing t
- When bodies are at such a distance from each other as the ea
- Perhaps you have never reflected upon all the reasons, why t
- This method, of interrogating Nature by experiment and obser
- These relative distances are found in two different ways; fi
- In the next place, let us see how valleys and deep craters i
- The changes of the moon, commonly called her _phases_, arise
- The figure of the moon's orbit is an ellipse. We have before
- As the sun and earth are both situated in the plane of the e
- This method of taking the longitude seems so easy, that you
- THERE is no study in which more is to be hoped for from a lu
- Transits of Mercury occur more frequently than those of Venu
- The entrance of one of Jupiter's satellites into the shadow
- In the year 1624, soon after the accession of Urban the Eigh
- Figure 60, facing page 247, represents Saturn, as it appears
- The most surprising circumstance connected with the discover
- Kepler was born of parents who were then in humble circumsta
- NOTHING in astronomy is more truly admirable, than the knowl
- The next return took place in 1607, when the comet was obser
- Nothing can convince us more fully of the complete mastery w
- After collecting and collating the accounts given in all the
- Thirdly, its period of revolution must have either been grea
- _Ursa Major_ (_the Great Bear_) is situated between the pole
- Beside these revolutions of the binary stars, _some of the f
- Pythagoras was the founder of the celebrated school of Croto
- In the second place, similar marks of wisdom are exhibited i
- The United States have contributed their full share to the r