What happened 1840 AD

In 1840, British scientist Warren de la Rue enclosed a coiled platinum filament in a vacuum tube and passed an electric current through it. The design was based on the concept that the high melting point of platinum would allow it to operate at high temperatures and that the evacuated chamber would contain fewer gas molecules to react with the platinum, improving its longevity. Although a workable design, the cost of the platinum made it impractical for commercial use.

In Germany, Peter Friedrich Voigtländer designed an all-metal camera with a conical shape that produced circular pictures of about 3 inches in diameter. The distinguishing characteristic of the Voigtländer camera was its use of a lens designed by Joseph Petzval. The f/3.5 Petzval lens was nearly 30 times faster than any other lens of the period and was the first to be made specifically for portraiture. Its design was the most widely used for portraits until Carl Zeiss introduced the anastigmat lens in 1889.

Douglass also joined several organizations in New Bedford, and regularly attended abolitionist meetings. He subscribed to Wm. Lloyd Garrison's weekly newspaper, The Liberator. Douglass later said that "no face and form ever impressed me with such sentiments [of the hatred of slavery] as did those of William Lloyd Garrison." So deep was this influence that in his last biography, Douglass confessed "his paper took a place in my heart second only to The Bible". Garrison was likewise impressed with Douglass, and had written about his anti-colonialist stance in The Liberator as early as 1839.

Douglass thought of joining a white Methodist Church, but was disappointed, from the beginning, upon finding that it was segregated. Later, he joined the African Methodist Episcopal Zion Church, an independent black denomination first established in New York City, which counted among its members Sojourner Truth and Harriet Tubman. He became a licensed preacher in 1839, which helped him to hone his oratorical skills. He held various positions, including steward, Sunday-school superintendent, and sexton.

Following the Queen's marriage in 1840, her husband, Prince Albert, concerned himself with a reorganization of the household offices and staff, and with addressing the design faults of the palace.

The first stone of the new Pugin-Barry design was laid on 27 April 1840, by Barry's wife Sarah (née Rowsell).

The Great Natchez Tornado hit Natchez, Mississippi, on Thursday, May 7, 1840. This tornado was the second deadliest tornado in United States history; at least 317 people were killed and at least 109 were injured.

In 1840, Douglass delivered a speech in Elmira, New York, then a station on the Underground Railroad, in which a black congregation would form years later, becoming the region's largest church by 1940.

It was signed on 15 July 1840 between the Great Powers of the United Kingdom, Austria, Prussia, Russia on one hand and the Ottoman Empire on the other. The Convention lent some support to the Ottoman Empire, which was having difficulties with its Egyptian possessions.

Lincoln in 1839 met Mary Todd in Springfield, Illinois, and the following year they became engaged.

At this point, the European powers again intervened. On 15 July 1840, the British government, which had negotiated with Austria, Prussia, and Russia to sign the Convention of London, offered Muhammad Ali hereditary rule of Egypt as part of the Ottoman Empire if he withdrew from the Syrian hinterland and the coastal regions of Mount Lebanon. Muhammad Ali hesitated, believing he had support from France. His hesitation proved costly. France eventually backed down as King Louis-Philippe did not want his country to find itself involved and isolated in a war against the other powers, especially at a time when he also had to deal with the Rhine crisis. British naval forces were ordered to sail to Syria and Alexandria. In the face of such displays of European military might, Muhammad Ali acquiesced. Muhammad Ali finally had to accept the convention on 27 November 1840.

In 1840, Louis Philippe I obtained permission from the British to return Napoleon's remains to France. On 15 December 1840, a state funeral was held. The hearse proceeded from the Arc de Triomphe down the Champs-Élysées, across the Place de la Concorde to the Esplanade des Invalides and then to the cupola in St Jérôme's Chapel, where it remained until the tomb designed by Louis Visconti was completed.