Lightning occurs when a massive electrical discharge takes place between two oppositely charged clouds. It may also occur when this discharge is between the ground and a charged cloud.The charges develop in thunder clouds due to the friction of water droplets with air as the droplets move up and down with the rising and descending air currents within the cloud. During a bolt of lightning, thousands of amperes of electricity flows through the air in a fraction of a second. This rapidly heats up die air along its path which expands very fast producing shock waves which we hear as thunder. Although the lightning and thunder are produced at the same instant, we hear the thunder later because light (3,00,000 km per second) travels faster than sound (343.2 metres per second).

It was marketed by the Rectigraph Company of Rochester, New York (USA) in 1907. The patentee of the Rectigraph machine was George C. Beidler, who conceived the idea four years earlier while working in an Oklahoma City land-claim office. The need for constant duplication of legal documents led him to search for a better means than retyping or laborious copying by hand, his initial experiments being made with an ordinary dry-plate camera. The prototype Rectigraph photocopier followed and was patented in 1906.

Sikhism originated in Punjab with the teachings of Guru Nanak Dev (1469-1539), who was born a Hindu. Conceived as a monotheistic faith, a sort of bridge between Hinduism and Islam, Sikhism, in fact, developed as a militant sword-arm for the protection of Hinduism. Guru Nanak Dev himself lived at a time when Babar was on his numerous invasions of India, culminating in the battle of Panipat, which brought in their wake unprecedented rapine and massacre of the Hindus. Guru Nanak’s message both to the Hindus and the Muslims was one of humanity, goodwill, compassion and high ethical conduct. He was followed by a series of high-minded Gurus.

Robert E. Peary, who explored Greenland’s coast in 1891-92, tried for North Pole in 1893. In 1900, he reached northern limits of Greenland and 83° 50′ N. In 1902, he reached 84° 06′ N. In 1906, he went from Ellesmere Island to 87° 06′ N. He sailed in the Roosevelt in July 1908 to winter off Cape Sheridan, Grant Land. The dash for the North Pole began on March 1 from Cape Columbia, Ellesmere Land. Peary reached the pole, 90° N on April 6, 1909.