I doubt they worked at all (in the implied manner). If they are as durable as stated, they wouldn't have deformed enough to create a vacuum on a paved road, let alone a oiled, dirt road. It's pure marketing rhetoric, as far as I'm concerned.

It's worth noting that they were an independent company and not part of the United States Rubber Company, which virtually monopolized the bicycle tyre industry via it's subsidiaries and control of patents for all four major tyre types.Being an independent, they chose the two most popular types at the time, the single tube and and the clincher. Ironically, they backed the wrong styles, with both being virtually extinct to-day, while the two less popular styles of that era eventually went on to dominate the market.