Answer: 20 years. Furnaces should last between 15 and 20 years, according to industry experts and the Department of Energy. Furnace filters, however, only hold up one to three months â and in order to avoid an expensive service call, it's crucial to change them on the manufacturer's schedule.
Lens Improvement. Later in the 16th century, Anton van Leeuwenhoek began polishing and grinding lenses when he discovered that certain shaped lenses increased an imageâs size. The glass lenses that he created could enlarge an object many times.
Like many inventions today there are disputes in origins of the original inventors. The same dispute applies to who invented the microscope. Dating back to the first century when glass was first invented, the Roman's were investigating the use of glass and how viewing objects through it, made the objects appear larger.acharias Jansen and the first compound microscope. Then, during the 1590's, two Dutch spectacle makers, Zacharias Jansen and his father Hans started experimenting with these lenses. They put several lenses in a tube and made a very important discovery.