I sure can't recommend an easy all-purpose text on the history
of science, but here are some of my favorite books on various
specific developments:
Kuhn, The Copernican Revolution, ISBN 0-674-17103-9
Weinberg, The Discovery of Subatomic Particles, 0-7167-2121-X
Ferris, Coming of Age in the Milky Way, 0-385-26326-0
(fun to read but not very scholarly)
For biology and geology, I like Stephen Jay Gould's books,
though some of his ideas are considered pretty controversial
by experts.
My favorite astronomy book, which covers some current research
but also has excellent historical asides, is First Light by
Richard Preston. My edition is 0-452-26170-8, but I believe
it's been updated recently.
Everyone should at least browse through Newton's Principia.
For a very readable primary source, look at Galileo's Starry
Messenger (Siderius Nuncius). One translation is 0-385-09239-3.