ARTHROPODA 



inward, prevented by the harder rock below 

 from going directly down. If a well is bored 

 n the outcropping ends, 

 will be forced up into it, perhaps flowing 

 freely at th- :-ling to the principles 



explained by the lower half of the illustration. 

 The name artesian was formerly re.-trirte<l to 

 flowing wells, and is derived from the province 

 of Artois, where this type of well was first 

 popular. 



Most arti-sian wells supply pure drinking 

 .xcelleut for domestic purposes and for 

 stock, though often containing minerals. Ar- 

 tesian wells are common in many regions where 

 surface water of good quality is not easily 

 obtained. In recent years a large number of 

 them have been bored in New Jersey and 

 other states east of the Appalachian Moun- 

 tains, and many cities now obtain their supply 

 of water from them. They are used extensively 

 for irrigation in Iowa, Kansas, Colorado, Mon- 

 tana and Texas, and are numerous in South 

 Dakota. Some wells are very deep. One in 

 Pittsburgh, Pa., is 4,625 feet, and one in Gal- 

 veston, Tex., is over 3,000 feet deep. The 

 deepest well in the world is at Leipzig, Ger- 

 many, 5,735 feet. For the method of sinking 

 artesian wells, see WELL BORING. 



ARTHROPODA, arthrop'oda. This term, 

 which comes from two Greek words meaning 

 jointed foot, is used to describe a very large 

 family of the animal kingdom, all the members 

 of which are characterized by having jointed 



392 ARTHUR 



appendages. The arthropods range from the 

 tiny beach fleas and water fleas to the lob- 

 - and khi crabs, and include the spiders 

 and scorpions, the cockroaches, grasshoi 

 and dragon flies, and the beetles, bees, butter- 

 flies, gnats and flies, so it may l>e readily be- 

 lieved that this is by far the largest of all the 

 animal families. The bodies as well as the 

 appendages are in joints or segments, and in 

 typical forms each segment carries a pair of 

 the appendages, which have special functions 

 to perform. Most of these are used for walk- 

 ing, but some are suckers, some are jaws and 

 others are organs of sense or offensive or 

 defensive weapons. 



The arthropods have an external skeleton or 

 shell, though in some members of the family, 

 as the flies or moths, this is so soft as scarcely 

 to deserve the name. In others, as the lobsters, 

 it is very hard and strong. All have an organ 

 which resembles a heart ; a well-organized nerv- 

 ous system, and simple or compound eyes. 

 See CRUSTACEA; MYRIAPODA; INSECTS, and the 

 articles therein referred to, with their various 

 illustrations. Read also, in this connection, the 

 article ZOOLOGY. 



Related Subjects. For a detailed discussion 

 of the animal forms belonging to this great 

 group, see the following articles, and the lists 

 included under some of them : 



Arachnida 

 Crustaceans 

 Hemiptera 

 Insect 



Lepidoptera 

 Myriapoda 

 Neuroptera 

 Orthoptera 



THE STORY OF CHESTER ALAN ARTHUR 



The White House In 1881 



RTHUR, CHESTER ALAN (1830-1886), 

 the twenty-first President of the United States, 

 one of the five men who have become Pres- 

 ident without being elected to that office; the 

 others were Tyler, Fillmore, Johnson and Roose- 

 velt. In the campaign of 1880 the Republican 

 party was divided; one faction, led by Conk- 



ling and Platt, favored the nomination of 

 Grant for a third term; the other was willing 

 to unite on any man to defeat Grant. The 

 man chosen was James A. Garfield, but to 

 appease the defeated Conkling faction the 

 Republicans nominated for Vice-President 

 Chester A. Arthur, one of Conkling's chief 



