POLITICAL SCIENCE. From the latter those organizations differ, where sovereign and legislature are common to two or more states, and all things tend to bring them into one consolidated form. Swe- den and Norway since 1814, Great Britain and Ireland, after the union of 1800, may serve as types of the former ; the three constituent parts of the United kingdom of Great Bri- tain and Ireland, of the latter. As this kind of union is rare and of little practical importance, we may pass it by in silence. We will look first at the compages of the Persian empire, and, in passing, at the Macedonian system in regard to subject states ; then somewhat more at large at the plan of Rome in regard to her colonies and conquests. In modern times the policy of Spain and England will call for our attention, after which the principal subject of this chapter, confederations, will be considered. Under Darius Hystaspes, the administration of the empire took the shape which it retained ever after- Persian empire. ,. . . wards. In the year 515 B. C., a division of the dominions was made into twenty provinces, the presiding officer over each of which was called a satrap or protector of the country.* Some of these satrapies were vast in extent and population ; thus Assyria and Babylonia formed one, and -^Egypt with Cyrene and Barca another. Subordinate divisions were made in some of them, and their principal officer received the name of a peckah, which is applied to Zerubbabel and Nehemiah, governors of Judah, and may be the origin of the modern title of pasha. The satraps would have become independent sovereigns, if care had not been taken first to appoint to this office, for the most part, Persians educated at the court, and then to inspect their administra- tion continually both in public and in secret ways. An un- * Bertheaii on Ezra viii., 36, interprets the Persian word Kshatra- pavan as meaning guardian of the land ; Duncker, Gesch. d. Al- terth., 11., 890, as guardian of the kingdom. Col. Rawlinson derives it from Kshatram, crown or empire, and pa, keeper, preserver. Comp. Prof. Rawlinson's note on Herodot., i., 192.