Museum of the History of Science, Oxford To view images of their drawing instruments click on "image library" and then enter drawing instruments in the search box http://www.mhs.ox.ac.uk
Old Scientific Instruments My collection of Dividers, Drawing Instruments, Surveying Instruments and Antiques Books from 15th to 18th Century. http://www.geometricum.com
Science and Society Picture Library To view images of the Science Museum collection. Many of the images can be viewed and printed without needing to register or sign in. http://www.scienceandsociety.co.uk
Scientific Collectibles and Slide Rules Dealer in Scientific items including nautical, survey, engineering instruments and slide rules. http://members.aol.com/sciant/index.html
Searching Patents. The Spire Project Details of patent databases in the USA and elsewhere and how to search them http://www.spireproject.com/patents.htm
Virtual Archive of Wild Heerbrugg Very interesting site covering Wild Heerbrugg and Kern. Some chunks are in German but overall it's very useful. http://homepage.hispeed.ch/dedual/wild_heerbrugg/index.htm
leadholder.com This site includes an extensive online gallery of drafting pencils, lead, and lead pointers. Other features include historical catalogs and patent documents for these instruments. http://www.leadholder.com