(almost none of this is about CountRumford--perhaps it should be moved)
Rumford was born 'Benjamin Thomas' somewhere in Massachusetts before the American Revolution. He studied fireplace design in order to get them to be less smoky and more effective at heating. His 'Rumford' design was so popular in the 19th century that fireplaces were commonly called 'Rumfords'. The difference is in the tall but shallow firebox, widely angled covings (sides of the firebox), and rounded throat.
After World War II, all interest in fireplace design was lost, due to ample supply of fossil fuels and central heating. Today, very few masons know how to build Rumfords, although the information is available in print. The original Rumford essays can be found in libraries, and some books have been published that resurrect some of the Rumford wisdom, while also trying to improve on it. Vrest Orton published such a book in the mid-1970's.
About ten years ago, Jim Buckley got his hands on the Rumford papers and built one of these fireplaces with success (they don't look like they could work). Since then, Jim's been busy getting national and local building codes updated to allow the Rumford design, and building and fixing fireplaces using Rumford principles. Jim also has a website with lots of information on the history and practical applications of this knowledge (http://www.rumford.com). Lots of nice pictures, too. For more information about Rumford himself, please visit Buckley's site.