Pneumatic Breakwaters

Collier's New Encyclopedia (1921)

a system of breaking the force of ocean waves invented by Philip Brasher and now used in the protection of several exposed piers on the Pacific coast. Perforated pipes connected with compressed air tanks are laid under water at the proper depths and beyond the pier to be protected. The rising of the wall of air bubbles through the water breaks the force and onward motion of the waves in much the same way as a shoal or submerged sandbar would do, and one great advantage of the air breakwater is that it forms no obstacle to navigation even when operating in storms. POISON GAS TREATY. (See WASH- INGTON CONFERENCE.) POLAND. New constitution adopted March 17, 1921. Parliament of two chambers elected by popular vote, malo and female. President elected by National Assembly and may be either Catholic or Protestant. In time of war, military responsibility shifts to Secretary of War. Equal rights to all religions. Free compulsory education. Freedom of language to all nationalities. Land holdings restricted, and other provisions include the care of orphans by the state and the prohibition of night work by women. March 18, 1921, treaty with Russia, in which Russia agreed to return expropriated property, to extend the Polish boundary, and to pay indemnity of thirty million rubles. Mutual abstention from propaganda. Polish-Lithuanian dispute over Vilna. (See VILNA, below.) PORTO RICO. (See UNITED STATES, 1921-1922.) PORTUGAL. This country was the scene of many political disturbances due to the revolutionary activities of secret societies among them the "Thirteen Club." On October 19, 1921, came an outbreak at Lisbon, in which the Premier and prominent supporters of his government were killed. A new cabinet was formed by Da Silva.