Here is a list of PDFs of books from the Victorian (and Edwardian) era that Steampunks can take ideas and illustrations from. There are many more that can be found, see my post on how to search to help you find them. Let me know in the comments if you find anything good!
Airships (1909)
http://www.archive.org/details/airshipalmanacli00browiala
Aircraft (1910)
http://www.archive.org/details/flyingmachinesc00jackgoog
The Aether (1886)
http://www.archive.org/details/luminiferousthe00woodgoog
Clockwork (1859)
http://books.google.com/books?id=9QnSAAAAMAAJ
Etiquette (1860s?)
http://www.archive.org/details/routledgesmanual00londiala
The Great Exhibition (1851)
http://books.google.com/books?id=lLgXAAAAYAAJ
The Magic Lantern (1888)
http://www.archive.org/details/bookoflanternbei00hepwrich
Mediumship (1891)
http://www.archive.org/details/experimentalspi00kardgoog
The Phonograph (1879)
http://www.archive.org/details/telephonemicrop00moncgoog
Steam Engineering (1867)
http://books.google.com/books?id=4Y5sBNn5NwAC
Steam Engines (1857)
http://books.google.com/books?id=w2UpAAAAYAAJ
Spirit Photography (1894)
http://www.archive.org/details/veilliftedmoder00taylgoog
The Telegraph (1860)
http://books.google.com/books?id=NK83AAAAMAAJ
The Telephone (1889)
http://www.archive.org/details/telephone01maiegoog
Theosophy (1891)
http://www.archive.org/details/isisunveiledama02blavgoog
The Typewriter (1890)