Yes, David has got it right.....it's
www.espacenet.com.
I visit it from time to time for work, but there is even some nice info to be found for our hobby.
You can download the whole Lindsey patent from there, but somehow it didn't work on my end. I was only able to download the drawings, but it would be just as interesting to read the text.
A search for Holmes also has some nice results:
http://v3.espacenet.com/textdraw?DB=...&QPN=US2264569
http://v3.espacenet.com/textdraw?DB=...&QPN=US2321549
http://v3.espacenet.com/textdraw?DB=...&QPN=US1657674
Also a search for Straussler resulted in some hits, but sadly his amphibious stuff is not available online.
I will take on your offer of the contacts for the C60X, but I also hope to find on or two in Beltring in three weeks. David and Hanno, will you be there, too?
Alex