Many techniques have been developed for the measurement of pressure and vacuum. Instruments used to measure and display pressure in an integral unit are called pressure gauges or vacuum gauges. A manometer is a good example as it uses a column of liquid to both measure and indicate pressure.
Figure 1: Timeline of mass extinction events. The five named vertical bars indicate mass extinction events. Black rectangles (drawn to scale) represent global reef gaps and brick-pattern shapes show times of prolific reef growth (Veron 2008). There have been five mass extinction events throughout Earth's history: 1  The first great mass extinction event took place at the end of the Ordovician, when according to the fossil record, 60% of all genera of both terrestrial and marine life worldwide were exterminated.
They estimate that more than one-tenth of these species are endangered. That adds up to at least one million kinds of plants and animals that could become extinct by the year 2015. In recent years the rate of extinction has increased too fast to too many species of plants and animals, in too many places.In the past 300 years, about 100 kinds of mammals have become extinct. Right now hundreds of birds, mammals, reptiles, amphibians, and fish are endangered, as well as more than 25,000 plants.The American Museum of Natural History in New York reports: Three species become extinct every hour of every day.n recent years the rate of extinction has increased too fast to too many species of plants and animals, in too many places. In the past 300 years, about 100 kinds of mammals have become extinct.