Our friends at Kaufmann Mercantile just published an interesting history of Weck canning jars on their blog. Turns out that although the name Weck is on the jar, the real Mr. Weck didn't invent the jars (he purchased the patent from its deceased inventor) nor was he around to grow the company into what it is today. In fact, Johann Carl Weck was only with the Weck company a few short years before he left to live in the French Alps at the turn of the 20th century.
Weck jars have been a popular canning jar in much of Europe but are somewhat new to American canners. They are gaining popularity, though, due to their good looks and the fact that they are BPA-free (the gasket is made of rubber.) Weck jars are not approved by the USDA for canning but from what I can gather, this is not because they are inherently faulty but due to the fact that the USDA has not tested them yet.
(Image: Apartment Therapy)