Ernst Engel, 1821-1896, was a Prussian statistician, founder of the International Statistical Institute and from 1860 to 1882 he was director of the Prussian statistical bureau in Berlin. However, he is best known for the formulation of his Engel’s law, deriving on what is known as the Engel curve.
Engel developed his famous curve in his book “Die Productions- und Consumtionsverhältnisse des Königreichs Sachsens” 1857, from observing and collecting data of the consumption patterns of Belgian working-class families, and he related their level of income with their expenditure in food and other goods. He observed that households with higher incomes tended to allocate a lower share of their income to food than poorer households. The Engel curve captures this inverse relation. His law is a reflection of this phenomenon and states this same relation. As Engel himself expressed, the implication of this law is very interesting in the macroeconomic sense as it implies that the higher the economic development of a country, the lower the share of agriculture will be in aggregate production.
Frank Plumpton Ramsey, 1903-1930, was an English mathematician who applied his knowledge and interest to the disciplines of philosophy and economics, resulting in remarkable contributions. Regarding his works on Economics, he produced three master pieces which were, however, disregarded for many years.
Eli Filip Heckscher, 1879-1952, was a Swedish economist who was Professor at the Stockholm University College and Director of the Institute of Economic History. His attention was centred in economic history and political economy, and he was in favour of 
Joe Staten Bain, 1912-1991, was an American economist. He spent his whole career as a Professor at the University of California at Berkeley, although he obtained his Doctorate in Harvard under 
John von Neumann 1903-1957, was a Hungarian-born American mathematician, who made important contributions to numerous fields. Regarding economics, he is well known for his contribution to 
Oskar Morgenstern 1902-1977, was a German born, American economist. He was Professor of Economics first in the University of Vienna and after at Princeton University. His most important contribution to economics was his joint development of 
Frank Hyneman Knight, 1885-1972 was an American economist and Professor at Cornwell University, the University of Iowa, and the University of Chicago, where he is considered as one of the founding fathers of the 
Joseph Louis François Bertrand, 1822-1900, was a French mathematician and economist who was Professor at the École Polytechnique and a member of the Collège de France.