Why does blotting paper absorb ink?

      

  It is mainly a question of the surface  of the paper. A very hard, very smoothly  glazed paper will scarcely absorb any ink.   If we write on such a paper, the ink takes a long time to dry; and what makes the  writing Is simply layer of the solid matier  left by the ink. This layer lies on the outside of the paper, and can almost be scraped away.    All other papers absorb ink to some extent. The drying of the ink means that the water of it has evaporated into the air, while the solids that were dissolved in it remain in or on the paper. But a paper  of loose texture, with a rough,  unfinished surface, like  blotting-paper, absorbs ink  just as sponge sucks up water.  The water of the ink, instead .   of mainly remaining on the outside of the paper until it dries, runs into the substance .  of the paper, according to the  amount of ink we use. That  is why the letters are not sharply defined when we  write on blotting-paper.

What did Galileo gaIiIei see when he turned the first telescope to the Sun?

   In the year 1611, Galileo, with the aid of his telescope, (picture, below) discovered that there were dark spots upon the Sun, and that those spots moved across the surface of the Sun from day to day. This was a very interesting and important discovery. though 'had terrible consequences tor Galileo. There was nothing to be found  about sun-spols in the writings at the great Greek thinker Aristotle,  I and so the people who were powerful In the time oi Galileo said  that what he called sun-spots were due to faults in his telescope or  in his eyes. 

    Worse than this, the discovery of sunspots was regarded as an insult to the Sun, as implying that he was not perfect, and therefore was a wicked thing to assert the existence of. But since the time of Galileo we have learnt to regard sun-spots as among the most interesting lhings in the Sun. When lafge ones are present, anyone can see them for himself by looking at the Sun through a smoked glass.If we watch them from day to day, we find, as Galileo himself found, nearly three hundred years ago, thaI ihey very often travel right across the face of the Sun, hom side to side. then disappear. and then appear again on the other side.   We notice also that as they reach the side of the Sun the-I seem to get narrower, as if we were looking at them sideways. This can only mean that the Sun splns round upon itself, and we now know that he takes rather more than twenty-five of our days to do this- lhat is to say, that while the Sun spins round once, the Earth spins round more than twenty-five times. The Earth's spinning makes day and night for us, but of course, it makes no difference to the brightness of any part of the Sun, which is the source of our day

What is El Nino? How does it affect the climate?

    In June 1982, aceanographers noticed a temperature rise in the surface waters of the eastern and central Pacific. The change, though barely discernible, marked the start of the most extensive Climatic disturbance on record, affecting places as far apart as Chile and Alaska, Indonesia and New York. According to climatolagists, the freakish weather worldwide sprang from conditions that give rise on a smaller scale to El Nino (the Christ Child), a periodic weather patlern that appears off South America shortly after late December. 

Scientists are now trying to determine how El Nina relates to the Southern Oscillatlon, a major seesawing in temperature and atmospheric pressure across the southern Pacific.   According to theory, El Nino arises when the trade winds slacken. Normally, these winds blow loward Asia, piling up water in thewestern Pacific. If lhey die down, warm'  water flows back toward South America,  displacing the cold Humboldt Current,  which travels up the coast carrying  nutrients vital to the marine food chain.  As a result, fish and bird life af e decimated  and the Peruvian anthovy and guano  industries ruined. Sometimes the trade  winds give out altogether, and associated  changes In air pressure brings torrential rains to Peru and Ecuador and drought to indonesia and Australia at the other end.  A major reversal in the seesaw would even affect weather in the Northern Hemisphere. The El Nino occurs due to abnormal transfer of heal between the ocean and atmosphere-but just what causes this imbalance is yet to be known completely. So far, researchers are nowhere near a complete analysis of the El Nino cycle.

Does light get fainter as it travels?

    We know that the farther off a bright thing is, the less bright it seems. The Moon, or a planet like Venus, is brighter than the stars to our eyes, though not a ten thousandth part so bright in reality,    because it is near. tight will travel on fOfever unless it is stopped. Still, somehow, light gets fainter as it travels.

The reason is that the light spreads in all directions as it travels, and so gets less intense at any particular place. If you have ever played with a magic lantern, you know what a bright spot of  light it throws when it is placed near the screen, but when it is moved farther away the light gets fainter as it gets wider. The law governing this is known precisely. If the distance is doubled, the light is one-fourth as bright; if the distance is triple, one-ninths bright; if quadrupled, one-sixteenth as bright. To get the intensity,  you must take the square of the distance- i.e., multiply it by itself, and then the intensity is so much less. We say that it varies inversely as the square of the distance. if it varied directly, then the light would be sixteen times as bright, when the distance was four times as great, instead of being one-sixteenth as bright. This 'law of inverse squares' is true for the intensity of light, sound, magnetism, heat, and gravitation.

Why do we lose the sense of smell when we have a cold?

    The sense of smell depends upon scented things in the air reaching the lining of our nose, especially certain small parts of the lining of  the nose. 

When we have a cold, this lining, or mucous membrane, of the nose gets swollen, and produces a muth greater amount of mucus than usual, as we all can tell by the number of handkerchiefs we have to use in a day. The chief reason why we cannal smell so well when we have a cold is, that this mucus,  constantly  pouring out of thelining of the nose and running over it, prevents the scent of things getting to the sensitive part of the nose, and washes away any solid scented  particles that there may be in the air. Also, it may very likely be that the poisons produced by the microbes that cause a cold, poison the living cells of the mucous membrane, and also poison the tiny ends of the nerves of smell that run to it, so  that even if scented air does reach the sensitive part of the mucous membrane, they cannot be felt.    This applies alike to scenls coming in from outside and also to the scents of food, which pass up at the back of the roof of the mouth inta the nose, and which, if we have not got a cold, help to give our food half its flavour.

Why does not the Moon make waves on rivers as well as on seas?

      The Moon does not exactly make the    waves of the sea, but it draws the sea after    it as the Earth spins, and as the sea usually    moves in waves, due to the wind, so the   tides rise and fall in waves. This is a wise   question, for we might think that the   water of river ought to behave as the   water of the sea does, and there is no   doubt that water everywhere, and every  liquid surface, and even the solid crust of  the Earth, is affected by the Moon.

 But the sea is deep, and so there is  enough water to be heaped up under the  pull of the Moon, and to make visible  tides. The water of a river is very shallow  in comparison with the sea, but near the  mouth of most rivers, where they merge  with the sea, the great tidal stream of water flows up and down the river as the tide flows and ebbs; and so the influence of the tides can be seen in these tidal rivers, perhaps many kilometres up from the sea.    Thus, tides can be noticed in the rivers like Garga, and in such cases the moon does 'make waves,' or rather, an inflow and outflow of water, in rivers.

Where did the expression, 'AII roads lead to Rome' actually come from?

       The expression grew from the tact that the ancient Romans built good roads radiating tram Rome to all parts of the country. At first -  these roads were just in Italy. Then, as the Roman  Empire stretched rorthward    into Western Europe  and  Britain,  the  highways lengthened.  Soldiers, travellers or  merchant caravans  were able to reach any  Roman province easily and  quickly. 

 

    The Romans were very thorough in their road building. They dug down until they struck clay or some other equally solid base.Then a layer of loose stones was put in, followed by a layer of smaller stones cemented together with mortar. Then came another layer ot even smaller stones and clay. The top layer, or surface, of the road was made of large, flat stones fitted and joined together with cement. So well were these ancient highways made that some were still in use a thousand years later, and traces of some (photo, above) can still be seen in parts of Europe.

Why do things fade if the sun shines on them?

    When such a thing as a curtain or a piece of cloth fades, it is because the chemical substances in it that give it its colour have been partly destroyed. Most of this Colouring matter Consists of substances which can be burnt, or oxidized, and if a thing is exposed to the air, of course there is plenty of oxygen round about it.

     The Sun's rays destroy the colour, because they help on this chemical change that we call oxidation. Every photograph is taken because of the power of the Sun's rays to  produce chemical changes, and the  fading of a piece of cloth exposed  to the Sun is really very much the same as what happens in a photographic plate. The part of the Sun's rays which has this chemical power is the part which produces the colours of blue and violet when it strikes our eyes, and also two or three colour-notes, as we might call them, higher up than the violet, which our eyes cannot see, and which are called ultraviolet.

Why can iron float on mercury if it cannot float on water?

    All questions of floating and swimming and flying depend on the comparative  differences between various things as regards gravitation. Iron is heavier than  water, or as we say, its specific  gravity is greater than that of  water.lron must therefore sink in water.

     

    Mercury is heavier than water and therefore mercury  must sink in water.     But mercury is heavier than iron, and it must therefore sink in iron, which is just a peculiar way of saying that the iron must float on mercury. The thing with the highest specifiC gravity is the thing for which the earth has the strongest pull. It therefore gets nearest to the earth, and anything eise must float on the top of it.

How many elements are there?

    There are about a 118 known chemical elements. A few of these elements have been produced in such atom-smashing machines as the cyclotron. These man- made elements are technetium (43); promethium (61); astatine (85); francium (87); neptunium (93); plutonium (94); californium (98); Einsteinium (99) etc. It seems unlikely that these manmade elements exist in a natural state. 

Scientists have been able to measure the approximate atomic weights of the different atoms. These weights do not tell   atom. instead, it has been found practical to use a system of relative weights; and in this system oxygen has  been  given  the arbitrary weight of 16. This weight was decided on because it was found that, when oxygen was given an atomic weight of 16. the weights of the other atoms compared to that of oxygen were generally close to whole numbers.ln this list the atomic weights have been rounded off to the   nearest   whole  i numbers.   tolumn three gives us the atomic numbers, which are useful because they tell us something about the complexity of the atoms. The structure of some atoms is exceedingly complex. Other atoms are comparatively simple. Atoms are listed in the order of their 'encresing Complexity by what is known as their atomic numbers. If you compare the atomic numbers and the atomic weights of the different atoms, you will see that, in most cases, the more complicated an atom the heavier it is.I the actual, absolute weight of each

Can anything boil when it is cold?

   Boiling is the changing of a liquid into vapour, or gas; and the temperature at which this happens iS called the boiling point of the substance.  The bailing point of water is generally given as 100℃, but the  according to the pressure  Water will bail at a lower temperature at the top of a mountain than at sea leveI At the top of Mont Blanc, for instance, water boils at 85℃. Some substances boil al a very much higher temperature than water. Gold, for instance,  melts  or becomes liquid, at 1063' ℃, and boils at 2600℃. Copper melts    at    1083' ℃ and boils at  2300 ℃ Silicon, which forms about a quarter of the Earth's crust, melts at 1420 ℃ and bails at 2600 ℃. Tin melts at 231 ℃ and boils at 2260 ℃. These are substances that are solid in the ordinary temperatures at which we live Mercury, or quicksilver, which is normally a  Iiquid,  boils at  37 ℃.   When we come to substances that are gases at ordinary temperatures, we find that their boiling point is very low. Hydrogen boils, or changes from the liquid into the gaseous slate, at minus 2530 ℃ . Fluorine boils at minus 187 ℃ centigrade; nitrogen at minus 196o; and oxygen at -183℃ .

Why are banana picked green?

    Bananas grow in great bunches. When first you see such a bunch hanging from  a banana tree, you may think that     the whole bunch has    been turned topsy- turvy. instead of  pointing toward  the ground, each banana points upward  so that the bunch looks as  though it has been turned upside down. The burich is cut from the tree while the bananas are still green, for if they were allowed to ripen on the tree the skin would break open and insects would crawl in upon the fruit, spoiling it for us. Fortunately, bananas ripen perfectly at room temperature. ,

Do the stars really fall down?

  The things that fall, and are called shooting stars, are really not stars at all. If a real star fell onto the Earth-or, rather, if the Earth fell into a star-we should all be burnt up by the heat, long before the Earth and the star  meet each other. The things that fall are really quite small stones, or pebbles, or balls of iron and other elements. 

They sometimes fall all the way to the Earth, and can be picked up afterwards. By far the greatest number of them, however, never reach the surface of the Earth as stones, or meteorites, atall, for they are burnt up, or broken up, into dust by the Earth's thick atmosphere. A very great amount of the dust in the air, especially in the higher levels of the atmosphere, is made of this meteoric dust. We see only a few of the falling stars that are caught by the Earth's atmosphere. Though they are falling all the time, we never see those that fall in the daytime. They become bright and hot as they pass through the air, but not bright enough for our eyes to notice when the Sun is shining upon our part of the Earth. Quite a lot of the present matter of the Earth has been derived from meteors, or falling stars, in this way. The meteoric dust can sometimes be found lying on the snow of the high peaks of mountains.i

Why do we swing our arms while walking?

  it is rather difficult to say exactly why we swing our arms when walking, but there is no doubt that it is much easier to walk in comfort if the arms are allowed to swing naturally than if they are held stiffly by the sides of the body. 

Probably, therefore, the swing  of  the  arms assists  us  in unconsciously keeping accu- rate balanCe as we   move along, first on  the and the  one f then  foot  on  other.  Perhaps,   it may be partly a relic of the time   when  K;    !  primitive animals used their arms as well as their legs in walking, as a chimpanzee will do. In any case, the fact is that it is so much more comfortable to walk swinging the arms. It seems that Nature may have intended the swinging to help us in accurate movement.i

How did the days get their names?

   It is often said that the days of the week were named after the planets of our solar system and the Sun and the Moon. 

It is much more likely that the days as well as the planets were named by the early peoples after their Gods.   Before the telescope was invented, men Could see only five planets, but they believed that the Sun and Moon were planets, making seven in all. Since seven was regarded as a magic number in those days, it may have seemed especially fitting to make the days of the week seven in number.    The names of the days as we know them in English came from the early Saxon or Norse day names. Sunday, of course, was the Sun's day. Monday was named after the Moon. Tuesday took its name from the Norse God of waf, Tiw, who was much like the Roman God, Mars. Wednesday was named for the Saxon God, Woden, who corresponded to the Roman God, Mercury. Thursday was Thor's day- Thor was the Norse Jove or Jupiter. Friday was named for the Saxon Venus-Freya-the goddess of beauty. Saturday is Saturn's day.i

What causes sore throats look red?

    Almost every corner of our body is liable to host a bacterial infection, and tissue at the back of the throat is no exception. The
,a condition marked by pain, redness, swelling, heat and loss of function. The specific cause of pain at the infected site-whether in the throat  Of elsewhere-remains something  of  a mystery.   It   is thought that various  ld  substances afe produced or released loCally that stimulate nerves to send a pain signal to the brain. The reddening represents an enhanCed blood flow at the site that Carries agents from the immune system to fight the infeCtion.    Although the inflammation may produCe temporary discomfort, it is actually beneficial. Studies have shown that, though they relieve unpleasant symptoms, anti-inflammatory medications reduce resistante to dangerous illness.

   redness and pain we associate with a sore throat are symptoms of inflammation that naturally accompany any infection. And though the redness may look horrid, it's a signal that the body has been mobilised to oust the invaders.   When human tissue is infected, it responds by becoming inflamed