In 1723 Bach moved to Leipzig to take the job of "Cantor" at the St Thomas Church, a very large church in the town. As "Cantor" he was in charge of all the music, both at St Thomas and at another church nearby. He also had to compose music for the town. It was an excellent job, and more secure than being at a court. The schools were good for his sons. Bach stayed in Leipzig until his death. He loved his job most of the time and worked very hard. He composed many cantatas for the church services. These services were very long, lasting about three hours. Many of the cantatas he wrote last about 30 minutes, and that was just one part of a service! He had assistants to play the organ. Bach himself directed the choir and the orchestra. There were probably 16 singers in the choir and 18 players in the orchestra. He wrote the "St Matthew Passion" and the "St John Passion". Both these works, which are very long, tell the story of Jesus dying on the cross. They are among the most famous pieces of music ever written. He also wrote cantatas for special occasions such as weddings or funerals.
Life was not always easy, and sometimes there were arguments with the people who ruled the church. The sub-deacon wanted to choose some of the hymns, but this was the "Cantor’s" job. Bach was a sensible man, and he managed to get his way without making enemies. On another occasion he argued with the headmaster of the school (Bach had to do some teaching at the church school) about who was allowed to choose the choir section leaders. This actually went to court, and Bach won the case.
Bach often made journeys to other towns. In 1747 he visited the court of Prussian King Frederick the Great near Berlin. The king, a music lover, gave Bach a theme to improvise from on the harpsichord. Bach sat down and improvised a fugue using this theme. Later Bach wrote a very long composition for flute, violin and harpsichord with cello accompaniment, in many movements, all based on this theme. At the end, the theme is heard in 5 of the 6 voices. Bach called it "The Musical Offering" and he sent it to the king.
Bach wrote many fugues, eventually he decided to write a collection called "The Art of Fugue". His plan was to publish it, but he died before he could finish it (his son later published it in his honor, as Bach's last published piece). In the last year or two of his life, he became blind in spite of two eye operations.
In the 19th century more people became interested in Bach, and many of his works were published after he had been dead more than a hundred years.
Atmosphere of Earth
The atmosphere is the layer of gases around the Earth. It is held in place by Earth's gravity.There are total 5 layers of atmosphere, named stratosphere, troposphere,mesosphere,thermosphere and exosphere. It is made up mainly of nitrogen (78.1%). It also has plentiful oxygen (20.9%) and small amounts of argon (0.9%), carbon dioxide (~ 0.035%), water vapor, and other gases. The atmosphere protects life on Earth by absorbing (taking) ultraviolet rays from the sun. It makes our days cooler and our nights warmer.
Solid particulates, including ash, dust, volcanic ash, etc. are small parts of atmosphere. They are important in making clouds and fog.
The atmosphere does not end at a specific place. The higher above the Earth, the thinner the atmosphere. There is no clear border between the atmosphere and outer space, though the Kármán line is sometimes treated as a border. Even higher, for some purposes the edge of the magnetosphere is treated as a border. 75% of the atmosphere is within of the Earth's surface.
Originally, the Earth's atmosphere had almost no free oxygen.
Some parts of the atmosphere are hot or cold, depending on height. Starting from the surface and climbing straight up, the air gets colder in the troposphere, but then it becomes hotter, higher in the stratosphere. These changes of temperature are divided into layers. These are like layers of an onion. The difference between the layers is the way the temperature changes.
These are the layers of the atmosphere, starting from the ground:
Where one layer changes to the next have been named "-pauses." So the tropopause is where the troposphere ends ( high). The stratopause is at the end of the stratosphere. The mesopause is at the end of the mesosphere.
These are called boundaries.
The average temperature of the atmosphere at the surface of Earth is .
The atmosphere has pressure. This is because even though air is a gas, it has weight. The average atmospheric pressure at sea level is about .
The density of air at sea level is about 1.2 kilograms per cubic meter. This density becomes less at higher altitudes at the same rate that pressure becomes less. The total mass of the atmosphere is about 5.1 × 10 kg, which is only a very small part of the Earth's total mass.
Human penis
The human penis is a male body part found on the outside of the body. It is used for urination and for sexual reproduction. The main sexual function of the penis is to be inserted into a female's vagina and deliver semen which may cause pregnancy. This activity is called sexual intercourse.
There are many slang words for "penis". They include "dick", "cock", and "schlong". A euphemism for "penis" is "male member".
The human penis exits the abdomen above the testicles and hangs freely outside the body. The main visible part is called the shaft.
The human penis is made up of three types of tissue. It has two corpora cavernosa (special pieces of muscle) next to each other and a corpus spongiosum (spongy muscle) between them.
The end of the corpus spongiosum forms the glans penis which is underneath the foreskin in uncircumcised males. The area on the bottom of the penis, where the foreskin is attached on uncircumcised men, is known as the frenulum. The urethra, the tube where urine and semen travel through, runs down the corpus spongiosum (spongy tissue), and opens at the tip of the penis. Sperm are made in the testes (ball-like organs) and stored in the epididymis (layer of tissue) around the testes. During ejaculation, sperm are pushed up the vas deferens. Fluids are added by the seminal vesicles, the prostate gland and the bulbourethral glands to make semen.
A penis can become erect if a male is sexually aroused (or sometimes during sleep, even though there is no sexual stimulation). In an erection, the penis fills with blood. The blood makes the penis become longer, thicker and harder. Veins taking blood away from the penis get smaller, so less blood is taken through. Arteries bringing blood to the penis get wider, bringing more blood to the penis.
Ejaculation is when semen is pushed from the penis. It usually happens during an orgasm. Males can ejaculate during sexual intercourse or by masturbation.
In reproductive sexual intercourse between a male and female, the erect penis is inserted into the vagina and moved in and out. The vagina places pressure on the penis, which can cause the male to have an orgasm and ejaculate into the vagina, causing insemination.
Other forms of sex, like anal and oral sex, can also cause stimulation, and therefore orgasm and ejaculation. In masturbation, a male can stimulate the penis and other sensitive areas of the body, such as the scrotum, by rubbing the genital area. Ejaculation may also happen during sleep (called a 'wet dream'). A male must have started puberty before he can ejaculate. During orgasm, muscles push semen from the penis. Semen moves through the urethra and comes out of the hole at the tip of the penis.