What is a lightship?

A lightship is like a floating lighthouse. It anchors in one spot to warn shipping of such nearby dangers as sand banks or dangerous currents. At night it projects a powerful beam of light. The lamp is fitted in such a way that the beam stays steady, even if the ship is being tossed about by waves. Lightships also have their name painted on each side, so that during daylight hours ships can use them to check their own position.

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What kinds of tools did early man use?

Some animals and birds make use of tools. There are some good examples among the birds. For example, the song thrush commonly feeds on snails which it opens by flying up with the shell in its bill and dropping the snail on convenient stone. The bird often uses the same stone on a number of occasions so that it may become littered with broken shells.
The stone is often referred to as a thrush’s anvil. The members of the shrike family often make use of thorns on which they impale their prey. But man more than any other animal has taken advantage of his large brain capacity to increase his power to hunt, kill, build his homes, and so on.
It is man’s ability to hold things in his hand with has enabled him to make such use of tools, where other animals have had to rely on their strength and agility, their teeth and their claws. Man’s first tools and weapons were stones which he had picked up. He chose stones that had been worn and sharpened by the weather into shapes that could be used as clubs or for cutting and scraping. As you might imagine the right shaped stones were not always easy to find, so that in time man learned to fashion primitive tools to a constant design that suited his purpose.
Many of the early men were carnivorous, that is, they fed largely on meat. This meant that a lot of the stones that have been positively identified as prehistoric implements were designed to kill animals, and then to scrape the flesh off the bones of the victim. Tools of prehistoric man could be made of bone, tooth, or more frequently stone, and in particular, flint. Flint was chosen because it breaks to give a flake with a very sharp, hard edge that could be used as, say, an axe. At first, these primitive weapons would be held directly in the hand. Eventually, however, man learned how to attach these axe-heads to a wooden shaft, and the power of the weapon was increased.
As he became more experience in making stone tools, the tools became more and more advanced in their design so that soon he was making blades, scrapers, and even arrowheads. Arrowheads were a great advance because they meant that for the first time man could kill his prey without putting himself to the risk of approaching what could be a very dangerous animal. Of course, these weapons could also be used to wound and kill other men.

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Are all deserts hot?

The definition of a desert is a place where the lack of moisture makes it impossible for anything but a few special life forms to grow. This applies not only to hot places, like the Sahara and the Gobi deserts, but also to very cold places too. Because all or most of the moisture there is turned to ice, almost nothing can grow there, which makes it a desert. So, you see, a great deal of the Artic is desert as well as the hot places people think of as being deserts.

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How are Clouds formed?

Clouds are formed when warm moist air rises into the sky. When it reaches a certain height, the warm air cools down and the water vapor in it condenses in to small drops of water, forming clouds. There are several different types of cloud. The ones which are highest are usually made up of drops of ice, and are the thinnest. These are called cirrostratus and cirrocumulus clouds. Lower clouds are called altostratus and altocumulus clouds. Lower still are the stratocumulus clouds and the nimbostratus clouds – these are the thick and shapeless rain clouds- and the lowest of all are the stratus clouds, which are seen as fog over high, mountains regions. Thunder clouds are called cumulus and cumulonimbus clouds, and these are the fat, cauliflower shaped ones.

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