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.
The first light microscope dates back to 1595, when Zacharias Jansen created a compound microscope that used collapsing tubes and produced magnifications up to 9X. Microscopes have come a long way since thenâtoday's strongest compound microscopes have magnifying powers of 1,000 to 2,000X.he first light microscope dates back to 1595, when Zacharias Jansen created a compound microscope that used collapsing tubes and produced magnifications up to 9X. Microscopes have come a long way since thenâtoday's strongest compound microscopes have magnifying powers of 1,000 to 2,000X.