1600-1699: Measurement and theory
Among the most important problems of the 17th century were those concerned with physical measurement- of time, distance, and space- for astronomy, surveying, map making, navigation and territorial expansion. This century saw great new growth in theory and the dawn of practice- the rise of analytic geometry, theories of errors of measurement and estimation, the birth of probability theory, and the beginnings of demographic statistics and "political arithmetic".
By the end of this century, the necessary elements were at hand- some real data of significant interest, some theory to make sense of them, and a few ideas for their visual representation. Perhaps more importantly, one can see this century as giving rise to the beginnings of visual thinking.
Tables of empirical data, published tables of numbers begin to appear. "Die Tabellen-Statistik," as a branch of statistics devoted to the numerical description of facts- Germany.
In 1617, the year of his death, Napier invented a calculating device, called "Napier's Bones," based on logarithms to facilitate multiplication and division. Napier was also the first to describe the systematic use of the decimal point in representing the result of long division.
In 1621, Willibrord Snell, in Cyclometricus, discovered the law of refraction which says that the ratio of the sines of the angles of incidence and refraction is a constant and the index of refraction varies from one transparent substance to another. This law implies that the velocity of light in a medium is inversely proportional to its refractive index. Cyclometricus was published after Snell's death by Rene' Descartes.
About 1629, Pierre de Fermat discovered that the equation $f(x,y)=0$ represents a curve in the xy-plane. This is the fundamental principle of analytic geometry, and was first published by Descartes in 1637. He also formulated a method for determining the maximim and minimum values which give single solutions for problems which in general have two solutions. This procedure is "almost precisely that now given in the differential calculus''" ''(Boyer 1949:156).
Graunt's work of 1662 is often ascribed to Sir William Petty. The authorship questionhas been discussed by Wilcoxwho concludes that although a portion ofthe work was by Petty, the majority is due to Graunt.
References:Graunt:1662 Petty:1665 Sutherland:1963 Wilcox:1937
E. H. Godfrey says that this is "a date prior to any modern census, whether European or American'', seeThe returns were fairly complete, giving data on population, sexes, families, conjugal condition, age, profession and trades, and they filled 154 pages. The original copy is now in the Archives of Paris, and a transcript in the Archives of Ottawa.