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.
He was also the first to record and observe muscle fibres, bacteria, spermatozoa and blood flow in capillaries (small blood vessels). Born in Delft, the Netherlands, on October 24, 1632, Anton van Leeuwenhoek (in Dutch Antonie van Leeuwenhoek) was the son of a basket maker. history of the compound microscope. Anton van Leeuwenhoek (1632 - 1723) was a Dutch tradesman and scientist, best known for his work on the development and improvement of the microscope and also for his subsequent contribution towards the study of microbiology.