A seismic source is a device that generates controlled seismic energy used to perform both reflection and refraction seismic surveys. A seismic source can be simple, such as dynamite, or it can use more sophisticated technology, such as a specialized air gun. Seismic sources can provide single pulses or continuous sweeps of energy, generating seismic … Read more
Seismology (pronunciation: /saɪzˈmɒlədʒi/; from Ancient Greek σεισμός (seismós) meaning “earthquake” and -λογία (-logía) meaning “study of”) is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other planet-like bodies. The field also includes studies of earthquake environmental effects such as tsunamis as well as diverse seismic sources such … Read more
For our purposes, it is convenient to assume that the earth is stationary and the sun is in motion around the earth. Figure V-1 lists the angle (declination) of the sun above (+) or below (-) the equator, on the twentieth of each month, as seen from the earth. From the Northern Hemisphere, you can … Read more
A sundial is a device that uses the position of the sun to tell time. Sundials work by casting a shadow on a marked surface, with the length and direction of the shadow indicating the time of day. The earth’s declination, or the angle at which the earth’s axis is tilted relative to its orbit … Read more
A good sundial has the shadowing edge parallel to the earth’s axis of rotation. The angle of rotation then is measured as the shadow move in a plane perpendicular to the earth’s axis. This can be constructed by sticking a broomstick out from the roof on ones house at an angle with respect to the … Read more
Definitely give it a try. It’s really fascinating. The one I made was one of the really simple cardboard ones – just a box nestled inside another box that was an inch or two bigger all the way around, with crumpled newspaper filling the spaces between them. I glued foil to the inside of the … Read more
A village is a clustered human settlement or community, larger than a hamlet but smaller than a town, with a population ranging from a few hundred to a few thousand. Though often located in rural areas, the term urban village is also applied to certain urban neighbourhoods. Villages are normally permanent, with fixed dwellings; however, … Read more