International Organization
These lists are very partial, including some of the more important meetings and institutions. In general, the number of organizations and conferences grew slowly from the 1860s to 80s, boomed in the 1890s-1900s, and boomed again after WWI.
International Conferences
1798 Metric System (Paris)
1851 Sanitary Standards (Parisfirst of many)
1852 Telegraphic Union
1853 Statistic (Brussels)
1856 Peace (Paris)
1863 Postal Union (Parisfirst of several)
1864 Marine signaling (London)
1864 Humanity in War (Genevasponsored by Red Cross)
1867 Monetary Standardization (Parisfirst of several)
1873 Mail (Paris)
International Meteorological Conference (Vienna)
1875 Metric treaty 1875
1878 Railway standardization (Bernfirst of several)
1880 Industrial Property (Paris)
1882 Protection of submarine cables (Paris)
Fisheries (Haguefirst of several)
1883 Exchange of Official Documents (Brussels)
1884 Time zoneswidely adopted by 1891
Copyright (Bern)
1884 Fixing the Prime Meridian (1994)
1885 Commercial Law (Antwerp)
Colonial Possession (Berlin)
1887 Liquor traffic (first of several)
1889 Maritime Law (Washingtonfirst of several)
Slave Trade (Brussels)
1890 Labor Legislation (Berlinfirst of several)
1893 Private International Law (Hague)
World Congress of Religions (Chicago)
1897 Ocean Telegraphy
1899 Peace (Hague, also 1907)
1903 Radiotelegraphy (Berlin)
1904 White Slave Trade (Zurichfirst of several)
1909 Opium (Shanghaifirst of several)
1910 Unification of Bills of Exchange (Hague)
Arial Law (Verona)
1911 Universal Races Congress
1913 Unification of the Law of the Check (Hague)
In addition, many conferences convened to discuss particular political and diplomatic issues. Many scientific congresses were also held, often with minimal government support.
International Governmental Associations
1864 International Geodetic Association
1865 International Telegraph Union.
1868 International Association of Women (private)
1874 International Postal Union
1875 International Penitentiary Commission
International Bureau of Weights and Measures
1883 International Union for the Protection of Industrial Prosperity
1884 International Rawilway Congress
1885 International Institute of Statistics
1886 International Union for the Protection of Literary and Atistic Works
1890 International Union for the Publication of Customs Tariffs
1897 International Maritime Committee
1899 Permanent Court of Arbitration
1901 International Labor Office
1903 International Associatieon of Seismology
1907 International Prize Court
Many, many more private international organizations were formed, especially in the 1920s.