After the French victory over the Arab Kingdom of Syria and the Balfour Declaration, clashes between Arabs and Jews took place in Jerusalem during the 1920 Nebi Musa riots and in Jaffa the following year. The Jewish Agency issued the British entry permits and distributed funds donated by Jews abroad. Between 1924 and 1929, over 80,000 Jews arrived in the Fourth Aliyah, fleeing Poland and Hungary, for a variety of reasons: anti-Semitism; in protestation at the heavy tax burdens imposed on trade; and the United States Immigration Act of 1924 which severely limited immigration from Eastern and Southern Europe. The new arrivals were mainly middle-class families who moved into towns and established small businesses and workshops—although lack of economic opportunities meant that approximately a quarter later left. The first electricity generator was built in Tel Aviv in 1923 under the guidance of Pinhas Rutenberg, a former Commissar of St Petersburg in Russia's pre-Bolshevik Kerensky Government. In 1925 the Jewish Agency established the Hebrew University in Jerusalem and the Technion (technological university) in Haifa. British authorities introduced the Palestine pound (worth 1000 "mils") in 1927, replacing the Egyptian pound as the unit of currency in the Mandate.