When he came to his senses, he was overcome with grief. He ran from other people and lived for a time in exile. He looked for advice from the Oracle of Delphi. The priestess sent him to serve King Eurystheus, King of Tyrins in Mycenae. In this way, she said, he would be washed clean of his crimes.
Eurystheus was a dull and bad man. Herakles hated him. Eurystheus set some tasks for Herakles to do. These tasks came to be called "The Labors of Herakles". It was said that Hera designed them. She hoped the tasks would kill him. Zeus would grant Herakles immortality with the successful completion of the Labors.
Herakles was married to a beautiful woman named Deianeira. They lived in Trachis and had a son named Hyllus. In a war with a neighboring city, Herakles made the king's daughter Iole his captive. Herakles had met her sometime in the past and had fallen in love with her. Deianeira was jealous, and used a mix of blood and semen from the centaur Nessus to get her husband back. She put the mix on a shirt and sent it to Herakles. He put the shirt on. Unknown to Deianeira, the mix was really a poison and burned Herakles' skin and flesh. Deianeira learned of this and killed herself. Herakles died in great pain. Before he died, he ordered Hyllus to marry Iole. Herakles' body was set on fire at the funeral ceremonies. His ghost fell to the underworld while his immortal part rose to Mount Olympus. The gods welcomed him, even Hera. He married Hebe, his fourth wife, and became the father of two sons. According to Homer's "Odyssey", Herakles became the porter (keeper of the gates) on Mount Olympus.
Steam engine
A steam engine is an engine that uses steam from boiling water to make it move. The steam pushes on the engine parts to make them move. Steam engines can power many kinds of machines including vehicles and electric generators.
Steam engines were used in mine pumps starting in the early 18th century and were much improved by James Watt in the 1770s. They were very important during the industrial revolution where they replaced horses, windmills and watermills to work machines.
The first steam engines were piston engines. The steam pressure pushed on a piston which made it move along a cylinder and so they had a "reciprocal" (back-and-forth) motion. This could move a pump directly or work a crank to turn a wheel and work a machine. They operated at low pressure and had to be very big to make a lot of power.
Steam engines were used in factories to work machines and in mines to move pumps. Later smaller engines were built that could move railway locomotives and steam boats.
The steam to power a steam engine is made in a boiler that heats water to make steam. In most places fire heats the boiler. Fuel for the fire may be wood, coal, or petroleum. Nuclear energy or solar energy may be used instead of fire. The steam coming out of the boiler applies the force on a piston. A valve sends the steam to one end of the piston, then the other, to make it move backwards and forwards. The moving piston pushes and pulls the piston rod, crosshead and connecting rod, to turn wheels or drive other machinery. The heavy spinning flywheel smooths out the power from the piston. The governor controls the speed of the engine.
Today many steam engines are still at work. During the 20th century the pistons were replaced by turbines which spin like a windmill pushed by jets of steam. These turn faster with more energy efficiency than the original kinds of piston steam engines. They are used in power plants to operate generators which make electricity. Some ships are also powered by steam turbines. The boilers of steam turbines can be heated by many different types of fuel, even a nuclear reactor in some power stations and warships.
Computer programming
Computer programming is the process of telling a computer to do certain things by giving it instructions. These instructions are called programs. A person who writes instructions is a computer programmer. The instructions come in different languages; they are called programming languages. There are many programming languages. Sometimes, programmers use special software, such as integrated development environments (IDEs), which have many special parts, including a text editor, to help them to type and edit programs.
Computers understand instructions directly if those instructions are written in machine code, special characters that can be processed by the computer but are difficult for humans to read. Writing these instructions directly in machine code takes a long time and is difficult, so instructions are written in a language easier for people to use, which the computer converts into "computer form" instructions (in other words, machine code) so the computer can follow them. The simplest of these is assembly language. Programs written in a language more like English are converted by a compiler. Some languages, called interpreted languages, use interpreters instead of assemblers or compilers.
Once a program has been compiled, the instructions in "machine form" are written into a file that contains a series of numbers that the computer can understand. These files are generally called "executables". These machine-instructions will be loaded into the computer's memory so that the CPU can run them when the executable is opened. In the event that data is not transferred correctly, it can result in data loss.
A variable is a piece of the program that can be changed. Variables can include information added by the user, or answers that are found as a result of a calculation.
Conditionals are parts of the program that work if something the program can check to see whether it is true. If that part is not true, then the program won't make it happen. A conditional is often done with an "If Statement".
Here is an example of an if statement in the Perl programming language. What it does is it checks to see if the name variable is Bill. If the name variable is Bill, then it will print out the words "Hi Bill!".
$name = "Bill";
if ($name eq "Bill") {
Sometimes, a programmer might want to have the "if statement" do something else if the first part of it is not true. This is known as an else block. Here is an example of an else block in the Perl programming language.
$name = "Ted";
if ($name eq "Bill") {
else {
And sometimes, the programmer might want to have multiple things for the if statement to do. For example, they may have the if block run if something is true, but will have parts of the if statement known as else if blocks that will run if the first part doesn't work, but if it works somewhere else. In the Perl programming language, else if is spelled like this, "elsif." Other languages might have it spelled like "else if" however. But for Perl, it is spelled like "elsif." Else If blocks will only run if their condition is true, just like the first if block. An if statement can have as many else if statements as the programmer needs. If the if block, and none of the else if blocks are true, then the plain "else" statement will be used by the program.
$name = "Ted";
if ($name eq "Bill") {
elsif ($name eq "Ted") {
elsif ($name eq "Alex"){
else {
In the program, a comment is information that is meant to be read by people who are reading the program. Comments have a special symbol in front of them that tells the computer that they are comments and should not be read as code.
Comments are used to explain how a certain part of a program works. This is helpful when multiple people are working on the same program, and if they need to work on a section where someone else was working on. If the programmer that was working on it first left behind comments for any other programmer that works on it later, it will help them know faster what is going on in the program.