You may download these highly informative articles in PDF format, free of charge, courtesy of authors Niles Eldredge and Arnold Myers, as well as the publications in which they were first published:
A Brief History of Piston-valved Cornets by Niles Eldredge
The Brasswind Production of Marthe Bessons London Factory by Arnold Myers and Niles Eldredge
The following article was originally published on VintageCornets.com, and is again presented:
The French Connection: Origin and Early Days of Périnet-Valved Bb Cornet Design by Niles Eldredge
"The Cornet Compendium: History and Development of the 19th Century Cornet" by Richard I. Schwartz. This extensive work traces the development of the cornet, as well as those who made and played them—an amazingly comprehensive resource!
Read free of charge online or Order Bound Copy direct from Author
Google Patents search engine is an amazing resource for learning about cornet designs, features and accessories. Search by maker, inventor, feature, patent date -- you name it.