In the nature there are several thousands of species of spiders from which a part is poisonous in different degree. Some of them pose threat for insects and animals, and some - and to the person. There are several species of spiders which are recognized as especially dangerous.
Phenol formaldehyde pitch, formula C6H3 (OH)-CH2-] n is a synthetic weight which has properties of thermoreactive plastic.
Transformers are the devices intended for transformation of tension of alternating current without loss to power. At input of the transformer in operation it is necessary to define its characteristics and to check their compliance to the parameters specified in technical documentation. A part of such works is determination of its resistance.
The era of the Middle Ages presented to the world many wonderful travelers who the works increased knowledge of people of the world. It is possible to distinguish the great Italian Amerigo Vespucci from the outstanding seafarers who wrote down the name in history.
The moon has an elliptic orbit and considerable eccentricity owing to what, it appears sometimes very close concerning Earth. But there are also other reasons for which the Moon in a firmament of extraordinary big sizes.