Here is the entire first paragraph of Jeans' essay. Were your predictions correct?
Because of the way it came into existence, the solar system has only one-way traffic, like Piccadilly Circus. The traffic nearest the center moves fastest; that further out more slowly, while that at the extreme edge merely crawls, at least by comparison with the fast traffic near the center. It is true that even the furthest and slowest of the planets covers nearly three miles every second, which is about 200 times the speed of an express train, but this is a mere crawl in astronomy. The planets Mercury and Venus, which constitute the fast traffic near the center, move, the former ten and the latter seven, times as fast. We shall find the reason for all this later; at present we are merely concerned with the facts.
Notice that Jeans ends this paragraph with a statement that lets you know what the rest of his essay will discuss: Why do the planets do this? But he also lets you know that he will first offer a few facts that he wants you to know.
Good writers have learned how to raises their readers' expectations, and then satisfying them. When a writer writes a sentence, he or she thinks carefully about what that one sentence leads a reader to expect or need to know, then he or she provides that information. One sentence may explain something in a the sentence before it, or it may define a term raised in the previous sentence. One sentence may offer an example of something mentioned in a previous sentence, or it may explain why the event in the previous sentence happened. One sentence may ask a question and the next sentence may answer it, or it may raise a problem and offer a solution.
The important thing to remember is that each of your sentences must relate to every other sentence around it. If you raise an expectation, make sure you satisfy it. Use these principles as you write and revise your future essays. And as always, If you have questions, you can contact me at closserb@andrews.edu