DEW 



1782 



DEWEY 



endish, of which the duke is the chief, has had 

 many distinguished members. The first duke, 

 William Cavendish (1640-1707), was conspicu- 

 ous in political affairs in the days of Charles 

 II and James II, and was one of the original 

 seven who invited Prince William of Orange 

 to the throne of England. He was created 

 Duke of Devonshire in 1694. The nephew of 

 the third duke was Henry Cavendish (1731- 

 1800), the famous chemist who discovered the 

 composition of water. The fifth duke, Wil- 

 liam (1748-1811), was the husband of Georgi- 

 ana, whose beautiful features were portrayed 

 by Gainsborough. The eighth duke, Spencer 

 Cavendish (1833-1908), was better known by 

 his courtesy title of Lord Hartington. He 

 was for years a leader of the Liberals, but after 

 Gladstone's conversion to Home Rule, Hart- 

 ington led a new party, the Liberal-Unionist. 

 On three occasions he might have become 

 Prime Minister, but each time preferred to 

 yield the honor to another. G.H.L. 



DEW. When you go into the garden on a 

 bright summer morning you find drops of water 

 on the grass, leaves and flowers, glistening in 

 the sun. What sere they? Where did they 

 come from? First, these tiny sparkling drops 

 are dew; second, they come from the air and 

 the ground. 



How Dew Is Formed. The atmosphere at all 

 times contains water vapor; the warmer the 

 air becomes the more vapor it usually contains. 

 When the atmosphere cools some of the vapor 

 is condensed and forms water. This is what 

 happens when a pitcher of ice water is set 

 in a warm room; the moisture that collects on 

 the outside of the pitcher is taken from the 

 air that comes in contact with it. Dew is 

 formed in the same way. At night the earth 

 gives back to the atmosphere some of the heat 

 that it absorbed from the sun during the day. 

 Most of this heat passes off through the blades 

 of grass and the leaves of plants, which become 

 cooler than the surrounding air, and they there- 

 fore condense the moisture in the same way 

 that the pitcher does. 



The largest quantity of dew is formed on a 

 clear, still night, when there is nothing to pre- 

 vent the radiation of heat or to disturb the 

 atmosphere. The layer of air next to the 

 earth then becomes cooled and gives up its 

 moisture. Wind prevents the formation of 

 dew, because it keeps the atmosphere in motion 

 and there is no chance for it to become cooled 

 by contact with the plants. Clouds often pre- 

 vent dew, because they reflect the escaping 



heat back to the earth and prevent sufficient 

 cooling of the plants to enable them to con- 

 dense the moisture. For the same reason dew 

 is seldom formed under trees or other objects 

 which reflect the heat back to the earth. 



Some of the dew on plants rises from the 

 earth in the form of vapor and is condensed 

 the same as that from the atmosphere. Those 

 objects which cool most rapidly collect the 

 most dew. A board, for instance, is a poor 

 radiator and collects but little dew, but large 

 drops may collect on the head of a nail driven 

 into the board. The ground under the board 

 is dry, because there is no chance for the heat 

 to escape from the covered ground. The 

 heaviest dews are in tropical regions, where 

 there is the greatest difference in temperature 

 between day and night. In regions having little 

 rainfall dew is of the greatest value to vege- 

 tation. When the temperature is below the 

 freezing point frost, instead of dew, is formed. 

 See FROST. C.R.M. 



DEWEY, GEORGE (1837-1917), an American 

 naval officer, known as the "hero of Manila," 

 the first American officer after David Porter 

 to be raised to the rank of admiral. His early 

 education was received in his home city, Mont- 

 pelier, Vt., and at 

 Norwich Univer- 

 sity. At the age 

 of seventeen he 

 entered the Naval 

 Academy at An- 

 napolis, graduat- 

 ing fifth in his 

 class. In 1865 he 

 received a lieu- 

 tenant's commis- 

 sion, was assigned 

 to the sloop Mis- 

 sissippi under 

 Farragut, and 



took part in the famous run past the forts 

 that guarded New Orleans. He was commis- 

 sioned lieutenant-commander in 1865 and 

 served on the Colorado and Kearsarge for two 

 years. In 1872 he was given command of the 

 Narragansett in the Pacific Survey. 



When war was declared between Spain and 

 the United States in 1898, Dewey was in Hong- 

 kong in command of the Asiatic squadron, 

 having risen to the rank of commodore. The 

 cable bore him this message: "Proceed at 

 once to the Philippine Islands. Capture or 

 destroy the Spanish fleet." Forty-eight hours 

 later his six vessels, with the Olympia at their 



ADMIRAL DEWEY 



