(1) Various agricultural schemes were floated, including, in the 1820s, a crackpot colonisation of Hawaii.

(2) In the 1820s, achromatic lenses were developed, and their use in compound microscopes provided investigators with the clearest images yet of tissue samples.

(3) The great turning point came in the 1820s and 1830s, when a group of people from different religious backgrounds began to demand the abolition of slavery in the United States.

(4) During the 1820s vintner's guides proliferated, and numerous periodicals printed recipes for making wine.

(5) In the 1820s the development of coiled springs fitted into mattresses revolutionized the Bed. In the Middle East Beds consisted of rugs piled up on the floor.

(6) In the 1820s Coffin moved west to Newport (now Fountain City), Indiana, where he opened a store.

(7) Born a slave two decades before, in the 1820s, Parker had been taken from his mother at age eight and forced to walk in chains from Virginia to Alabama, where he was sold on the slave market.

(8) In the 1820s, as it waged a war of independence against the Ottoman Empire, Greece became an early symbol of escape from the prison house of empire.

(9) George Canning, foreign secretary in the 1820s, exaggerated when he boasted "I have called the New World into existence(http://sentencedict.com), to redress the balance of the Old".

(10) Capt. James Cook sighted some of the islands in 1773; others were not discovered until the 1820s.

(11) The last time the volcano erupted was in the 1820s.

(12) It was probably the whole series of rebellions from the 1820s to the end of the Taiping that broke the Qing as a world power.

(13) The shaker religious community at Hancock, Massachusetts, built one in the 1820s.

(14) There is a big difference in how an American citizen voted in the 1820s and how that ballot is cast at the beginning of the 21st century.

(15) The first citation for pretzel in English comes in the 1820s in a collection called Antiquities of Long Island.

(16) Except for some minor eruptive activity in the mid-nineteenth century, the volcano has been inactive since formal records began in the 1820s.

(17) I like your story of Charles Babbage, who in the 1820s basically invented the concept of computer a century before anyone, including him, could make one.