ALGIERS 



198 



ALGONKIAN SYSTEM 



ALGIERS, fdjeen', a fortified seaport on 

 the African coast of the Mediterranean Sea, 

 formerly the most important Moorish city, now 

 capital of the French colony of Algeria. It is 

 advantageously situated partly at the foot and 

 partly on the slopes of a hill overlooking the 

 Bay of Algiers. The ancient Moorish section 

 on the hill above the modern portion preserves 

 the characteristics of Oriental cities many cen- 

 turies old. The modern city is a gay, electric- 

 lighted watering place, thronged with visitors. 

 The streets are broad and well kept, and there 

 are many fine squares. Prominent structures 

 are the Roman Catholic Cathedral, the Mili- 

 tary academy and its astronomical observatory. 

 Although changeable, the climate is very 



Algol loses five-sixths of its brightness at 

 regular intervals of three days. The diminish- 

 ing process la>ts four and one-half hours, and 

 the full brilliancy is recovered in a further three 

 and one-half hours. This is accounted for by 

 the presence of a satellite revolving about the 

 star and partially obscuring it when directly in 

 line between it and the earth. Measurements 

 show that the diameter of Algol is 1,160,000 

 miles; that of the satellite, 840,000 miles, and 

 that the two are about 3,250,000 miles apart. 

 Algol has a density equivalent to that of a 

 cork, and a mass about two-thirds that of the 

 sun. The distance of Algol from the earth is 

 so great that it cannot be expressed in figures. 

 See PERSEUS; MEDUSA. 



TWO SCENES IN ALGIERS 

 A street in the native section, and a public square in the modern part of the city. 



healthful, and particularly desirable for inva- 

 lids. Parisian manners and customs have been 

 transported to Algiers, which is said, though 

 incorrectly, to be "more French than Paris." 



The harbor and docks have been greatly im- 

 proved since the French occupation of the city 

 in 1830. Extensive commerce is carried on 

 with France, Italy, England, Spain and other 

 European countries. Algiers exports flour, 

 esparto, wine, olive oil and fruit, and is the 

 most important coaling station on the Mediter- 

 ranean Sea. In 1910 the population was 590,000. 



ALGOL, al' gahl, in astronomy, a variable 

 star in the constellation Perseus, forming part 

 of "Medusa's Head," which in the account in 

 mythology Perseus carried in his hand, to turn 

 his enemies to stone. The name is derived 

 from the Arabic al ghul, meaning the ghoul or 

 destroyer. For more than a century it was 

 known to be variable and was a puzzle to as- 

 tronomers. It has now been ascertained that 



ALGONKIAN, algon'kian, SYSTEM, the 

 term used by the United States Geological Sur- 

 vey to specify a great layer of rocks lying be- 

 tween the Archean System, below, and the 

 Cambrian, above. Algonkian is used synony- 

 mously with the term Proterozoic, which has 

 been adopted by many geologists (see GEOLOGY) . 

 It is the first, therefore the lowest, layer of 

 those rocks in the earth's crust which were 

 formed from sediment deposited at the bottom 

 of large bodies of water and hardened into 

 rock. Such rocks are known as sedimentary. 

 They contain few fossils, indicating a meager 

 development of life at the time of their for- 

 mation, but on the other hand proving the 

 existence of life. Outcroppings of the Algon- 

 kian System appear in the Lake Superior re- 

 gion, in Southwestern Minnesota, Missouri, 

 Texas, and in the Rocky Mountains. Most 

 geologists call the period in which they were 

 formed the Proterozoic Era, meaning the time 



