These resources will help you find primary sources on your topic, including correspondence, photographs, maps, government records and original drawings and notebooks.
These curated online collections are a great place to get started looking for topic ideas, or, if you know your topic, search for online exhibits here: http://www.sil.si.edu/SILPublications/Online-Exhibitions/search.htm.
The library has print copies of Nature (from 1869) and Scientific American (from 1916). These are a great place to look for articles on inventions, innovations or science topics from a historical perspective. You can use the links below to browse for the articles you want, and then you can find the magazines on the third floor of the library. (If you need help locating them, just ask at the Reference Desk.) We have several (free) scanning stations on the first floor, where you can scan copies of the pages you want.