Start a sentence with "Back in the day..." and you'll likely cause whoever is listening to tune out. However, reminders of the "old days" can spark gratitude for the changes that have made our lives more convenient. One example is the evolution of vacuum cleaners over the centuries, from clunky hand-powered or horse-drawn machinery to compact hands-free appliances. When it comes to cleaning, homeowners have seen immense growth in science and technology — both of which largely influenced the changes in vacuums. It didn't involve as much muscle power, but it still wasn't as effective as today's vacuums.