Metal

 maximum and minimum thermometer is a popular thermometer among gardeners for use in greenhouses. Its purpose is to record the maximum and minimum temperatures reached since the thermometer was last read. Generally speaking a minimum temperature occurs during the night and a maximum during the day. It was invented by James Six towards the end of the eighteenth century, and consists of a fairly large cylindrical bulb full of alcohol, or oil of creosote, connected by a U- shaped stem to a second bulb nearly full of alcohol or oil of creosote. The bend of the U contains a thread of mercury. Two scales are provided, one against each limb of the tube so that the temperature may be read against either of the mercury levels. Resting on each of the mercury surfaces are small steel indexes provided with light springs to hold them in position in the stem. Expansion or contraction of the fluid in the larger bulb causes a movement of the mercury thread. Consequently, one or other index is pushed forward by the mercury and left in the extreme position reached. Thus, the lower end of the index on the left indicates the minimum and that on the right the maximum temperature attained. It is interesting to note that Six's maximum and minimum thermometers were still being used in 2000 of exactly the same design and construction as ones produced over 100 years ago. Anonymous natural environment encompasses all living and non-living things occurring naturally on Earth or some region thereof. It is an environment that encompasses the interaction of all living species.[1] The concept of the natural environment can be distinguished by components: * Complete ecological units that function as natural systems without massivehuman intervention, including all vegetation, microorganisms, soil, rocks,atmosphere and natural phenomena that occur within their boundaries. * Universal natural resources and physical phenomena that lack clear-cut boundaries, such as air, water, and climate, as well as energy, radiation,electric charge, and magnetism, not originating from human activity. The natural environment is contrasted with the built environment, which comprises the areas and components that are strongly influenced by humans. A geographical area is regarded as a natural environment. Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia orMetazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and independently. All animals are also heterotrophs, meaning they must ingest other organisms or their products for sustenance. Most known animal phyla appeared in the fossil record as marine species during theCambrian explosion, about 542 million years ago.