A microfiche is a single sheet of plastic that contains several images of pages of text, whereas microfilm is a long spool of plastic film that winds and rewinds to view images of text. In both instances, these microforms require a projection system whereby images of microfiche and microfilm appear on a backlit screen to be viewed.Know More
Microfiche is usually 6 inches by 4 inches per sheet. Users place microfiche under a plate of glass. Once under the glass, light shines behind or beneath the plastic microfiche while a lens increases the image size. The image from the lens is then projected onto a small screen so individuals can read the text.
Microfilm is viewed in much the same way, only spools move microfilm back and forth under the plate of glass similar to a spool of movie celluloid. Microfilm holds many more document images than a single sheet of microfiche. Technology has improved to allow microfilm and microfiche images to be viewed on digital computer screens using special programs.
One of the largest microform collections in the world is housed at the Library of Congress. More than 7 million pieces can be viewed by researchers in the Microform Reading Room. The collection includes ancient manuscripts, posters, photographs, archives, rare publications and artifacts.Learn more about Public Records
Soil forms from a parent material deposited at the surface of the Earth, such as weathered bedrock or small materials carried by blowing winds, moving glaciers and flooding rivers. The parent material transforms or changes into soil over time. The major factors that affect soil formation are parent material, climate, landscape, living organisms and time.Full Answer >
Air masses move with the winds. One of these winds is called the jet stream, also known as a "steering wind."Full Answer >
Gymnosperms share four common characteristics: they lack a protective outer covering around their seeds, do not produce flowers or fruits and are pollinated by winds, which disperse their seeds over short and long distances. Physically, gymnosperms have distinct characteristics, such as color and size, which set them apart from similar plants.Full Answer >
Hurricanes affect an ecosystem due to their damaging winds and excessive amounts of rainfall; the winds are able to take down entire tracts of forests while the winds and rain combined can change the layout of an area. Animals that lived in the trees or had their home taken away by land changes often experience a decrease in their populations.Full Answer >