My Science School

          Electronic mail is a modern method of instant delivery of letters without the involvement of a postman. In this system of mailing, messages are sent with the help of a computer.

          In the electronic mail system a letter or any other document is typed and edited on a computer. It is then sent to the addressee through a computer network in the form of electrical signals. The addressee may be anywhere in the world but he should also have an electronic mail system. The contents of the transmitted letters or documents get displayed on the screen of the computer of the addressee. If he desires, he can get the message printed. If the addressee is absent, the transmitted matters will be automatically stored in the computer’s memory. When he returns the computer will give an indication that some mail is waiting for him.

          With the help of electronic mail system both typed and handwritten matters can be transmitted. Electronic mail is very fast and saves time and paper work but at present it is very costly. It needs a satellite, telephone and cable links with television, voice and computer data telecommunications. The electronic mail system has so far not been feasible for individual households. This system is being used by developed countries on a large scale.

          Email is widely used in Internet Services. It is also connected to other systems in which exchange of Email are being made effectively.

 

 

           In the 18th and 19th centuries, science fictions with an element of horror became quite popular with the masses. An Englishman named Horace Walpole first introduced horror as a permanent feature in most of his writings during the 1760s. Since then many writers started writing such stories including science fictions with amazing success. The Frankenstein’s monster is one such example that attained worldwide popularity.

           The story of Frankenstein was published in 1818 which had a scientific flavour with imagination. It is about the creation of a monster that ultimately destroys its creator. With its elaborate narrations of mystery, horror, outrage, madness and spirit of revenge - this character maintains the trend first started by Walpole. The basic idea behind the creation of the monster was to show the power of science - how a dead person becomes alive and the subsequent consequences of it. The trait induced in Frankenstein makes it a reactive and suffering creature that wavers between good and evil.

           But do you know who the creator of Frankenstein - the monster was? She was Shelly Mary Wollstonecraft, the daughter of William Godwin and second wife of the famous poet P.B.Shelly. She was born on 30 August 1797 in London. She spent much of her life editing her husband’s works after his death. Among the novels she wrote, the most famous was Life and Adventure of Castruccio.

           However, in spite of her many notable works, her name is mainly attached to the creature she portrayed in Frankenstein. This novel was transformed into feature films in many versions all over the world.

           Mary Shelly died on 1 February 1851 at the age of 54. 

               You will be surprised to know that there are some plants which catch and eat insects. Such plants are called insectivorous plants. Since they cannot prepare their own protein, they get it by eating insects and worms. Every plant of this kind uses it own technique for capturing insects. The leaves of these specialized plants are adapted to trap and digest insects - which supplement their food supply.

               One of the famous insectivorous plants is ‘pitcher plant’. The upper part of its leaf resembles a small pitcher. Its colour is very attractive. It contains a sticky liquid. The opening of the pitcher has small fibres which allow the insects to go inside but obstruct their coming out. On being attracted by the beautiful colour, when some insect enters this pitcher, it is unable to come out. It gets entangled in the juice of the pitcher and the plant produces certain enzymes and digests it. The ‘cobra plant’ of America which appears like a snake, also eats insects. It also has pitcher-shaped mouth.

               The ‘sundew plants’ have hair on their leaves. The tips of these hairs have droplets of a liquid which appear very attractive. As soon as some insect is attracted towards a leaf, these hairs bend forward, capture the insect and digest it with the help of their own juice. The digested flesh is absorbed through their leaves. After that the hairs again become normal.

               There is a plant called ‘venus-fly trap’ which is found in America. Its leaves have beautiful red coloured elevations on both sides. Whenever an insect sits on a leaf it closes like a fork and the plant digests the trapped insect by digestive juices. The ‘uticularia’ is a water plant. It is found all over the world. The roots of this plant which are submerged in water have bulbous bladders. When some aquatic insects enter the bladder, the hairs on its opening do not allow it to come out. The walls of these bladders give out digestive juices which suck the proteins out of the bodies of these small insects.

Similarly, a plant called ‘Indian pipe’ is found in the hills of Shimla. It also eats insects. In addition to these, there are many other insectivorous plants all over the world.

 

           The main device used to detect and locate objects like submarines and torpedoes under the sea water is called ‘sonar’. The word ‘sonar’ is an acronym for ‘sound navigation’ and ranging. This instrument is particularly useful in sea warfare. However, in peace time also, this is used in ships and submarines. It can locate objects at distances ranging from 100 metres up to 10 kms.

           Sonar mainly consists of two parts: the transmitter and the receiver. Both these parts are submerged in the sea water. The transmitter with the help of a transducer produces sound waves of high frequencies (5,000 to 300,000 hertz). These waves are called ultrasonic waves and cannot be heard by human ears. The transmitter transmits these waves in pulses in all the directions. Whenever these pulses strike some object inside the sea water, they get reflected. These reflected waves are received by the receiver. The time taken for the waves to reach the object and come back to the receiver is measured. Half of this time when multiplied by the speed of sound in sea water gives the distance of the object. This instrument contains a display device also, which accurately shows the distance and position of the object. 

           Sonar, however, is not a foolproof system. The sounds produced by some aquatic animals sometimes interfere with its transmissions and can be misleading about the position of the objects. The enemy submarines can be detected by this equipment and thus can be destroyed. These days there are various kinds of sonars being used for studying the objects inside water. Sonars also help in large scale fishing by locating those spots where large groups of fishes are present. Nowadays blue-green laser pulses are also being used for underwater detection of submarines and torpedoes. Laser based devices also work on the echo sounding principle just as a sonar works.