The development of Buenos Aires must be studied separately. It does not merely reflect the success of the colonization of the Pampa; it is a phenomenon of a national order. The attraction of Buenos Aires has been felt throughout the whole land. In 1895, of a total population of Argentine birth of 318,000 souls, more than a half--167,000--were born in the provinces.[146] The way in which the prosperity of Buenos Aires is bound up, not only with that of the adjacent territory but with that of the whole country, is seen in the stability of the figure representing the number of the inhabitants who have come from foreign lands. While the proportion of foreigners in each of the provinces varies from one census to another, according to the displacements of the stream of colonization, it remains almost the same at Buenos Aires: 496 per 1,000 in 1869, 520 in 1895, 493 in 1914. [146] The 1914 Census does not give reliable details on this point. The population of the city of Buenos Aires was estimated by Helms in 1788 to be between 24,000 and 30,000. D'Azara put it at 40,000 in 1799. The Revolution did not interrupt its growth. According to the estimate of Woodbine Parish the city had 81,000 inhabitants in 1824. On the other hand, the Rosas Government involved a period of stagnation (90,000 inhabitants in 1855). But after 1855 Buenos Aires resumed its progress, even before the political unity of Argentina was re-established, and has never since relaxed. Its population has doubled almost regularly at intervals of fifteen years: 177,000 in 1869, 433,000 in 1887, 663,000 in 1895, and 1,575,000 in 1914. The latter figure, in fact, is inadequate. Greater Buenos Aires, including the outlying parts, has really 1,990,000 inhabitants. The site on which the city is built is a regular plateau, sixty-five feet above sea level, cut by flat-bottomed, marshy valleys. The Riachuelo, at the mouth of one of these valleys, provided Buenos Aires with its first port. The low and badly drained lands of the valleys are occupied by the poorest quarters. Their sides, the _barrancas_, bear the aristocratic residences, and the gardeners have been able to use the sites to great advantage in their plans.