Civil engineer, Botnist and Geographer. Member of a number of the Academy of History, the Academy of Physical Sciences, Matematicas and Naturalist of Venezuela and the Venezuelan Society of Natural Sciences. Decorated with the Order of the Liberator. Been born in Caracas Venezuela on October 8, 1867, died in Caracas the June 12, 1940 at almost 73 years of age.His parents were:
- Alfredo Federico Jahn (Friedrich Gottfried Alfred Jahn Wassmann) born in Caracas on June 10, 1846
- Eugenia Hartmann born in Bremen, Germany on July 8, 1847
He was married in Caracas to Aurelia Lopez and had 10 children:
As a Civil Engineer, he worked with German Jimenez (Civil Engineer and Lawyer) in the National Plan of Highways and Railroads of Venezuela by order of the National Government. Works on the construction of the railroad from Caracas to Valencia. Built the highway from Caracas to El Junquito.
- Maria Aurelia Jahn Lopez born in Caracas on June 13, 1892
- Eugenia Jahn Lopez born in Maracay on August 23, 1893
- Alfredo Jahn Lopez born in La Victoria on April 4, 1895
- Gustavo Jahn Lopez born in La Victoria on July 25, 1896
- Margarita Jahn Lopez born in La Victoria on October 6, 1898
- Carlos Jahn Lopez born in La Victoria on December 19, 1899
- Luisa Cristina Jahn Lopez born in La Victoria on June 21, 1901
- Carmen Jahn Lopez born in Caracas on January 31, 1904
- Angelina Jahn Lopez born in Caracas on May 27, 1905
- Isabel Jahn Lopez born in Caracas on January 30, 1910
As a geographer he made the rise of the Lake of Valencia and all its river basin hidrografica. (all the rivers that falls in) and determined all the heights of the Mountain range of the Coast.
He lived with the Indians of the West of Venezuela and wrote books on their customs and dialectos. As Botnist he classified many plants in Venezuela and wrote a book on the Palms of Venezuela. (the Palms of the Flora Venezuelana - Caracas 1908)
He was one of the first Venezuelans to climb to the top of peak Bolivar in the Sierra Nevada of Merida.
He formed part of the Meeting of Direction and Promotion of the Tovar Colony (Colonia Tovar) in 1934.