Seismic Source

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

The Sun Charts How the Sun Works

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

Sundials Earth’s Declination

K.P. Cheung, Department of Architecture, The University of Hong Kong,Pokfulam Road, Hong KongThis page started in July 1997 TABLE 1 – Mean value of the solar declination (for l99l, noon UT (GMT), adapted from TheNautical Almanac l99l, HMSO, UK, p.10-253)

Subject: Re: Solar Ovens

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