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.
Even Galileo dririnya claim as the creator of the first that has made this tool in 1610. Galileo completed the manufacture of microscopes and microscope in 1609 he made the same named inventors, the Galileo microscope. This type of microscope use optical lenses, so-called optical microscopes. The microscope is assembled from the optical lens has a limited ability to increase the size of the object.