Q: I recently bought a vacuum cleaner at an estate auction. It was patented on Dec. 26, 1911. The vacuum has an emblem that says “The National” and is trademarked “The National Combination Vacuum Sweeper.” Underneath that it says “Hugro Mfg. Co., Warsaw, Ind.” Inside the bottom cylinder is a green felt lint bag. The auctioneer called it a crop duster, but I knew what it was and think I got a bargain. I paid $50 for it. What do you think?

A: This is a manually-operated plunger-type vacuum cleaner. The patent was issued to Charles Boyer of Marengo, Illinois, for “new and useful improvements in vacuum cleaning-machines.” His invention included an improved method of removing dirt from the air filtering bag and a method for keeping the bag in an expanded position. Hand-pumped vacuum cleaners were first used in the 1860s. A gasoline-powered vacuum cleaner was invented in 1898 and a vacuum powered by an electric motor was invented in 1901. Electric suction sweepers were available in 1907, but manually-operated vacuum cleaners continued to be used in rural areas that didn’t have electricity until the 1930s. Your vintage vacuum cleaner is missing the piece that fits on the pointed end and sweeps the floor. It makes a good conversation piece, especially with the story about the crop duster, but isn’t worth more than the $50 you paid for it.