The Sheridan Libraries at Johns Hopkins University has recently acquired a collection of 280 rare books and manuscripts concerning scientific discoveries.  Included in the collection are a 1495 edition of the works of Aristotle; a 1613 first edition of Galileo's illustrated treatise on the discovery of sunspots; a 1687 first edition of Newton's The Principia; and the first print appearance of Darwin's Theory of Evolution in 1858. There is a small slideshow of selected images here.

Johns Hopkins library obtains rare editions