Jean Nicolas Fortin

Jean Nicolas Fortin (1750–1831) was a French maker of scientific instruments, born on 9 August 1750[1] in Mouchy-la-Ville[2] in Picardy.

Among his customers were such noted scientists as Lavoisier,[2] for whom he made a precision balance,[3] Gay-Lussac,[2] François Arago[2] and Pierre Dulong.

This allows for the fact that, when the mercury column in the closed tube falls, the level in the cistern rises, and the difference in height between the two cannot be accurately determined unless the height of the latter is taken into account.

[5] In 1776 Fortin produced the Atlas céleste de Flamstéed, a revised and updated edition of Flamsteed's Atlas Coelestis (celestial atlas) of 1729, at about 1/3 of the original scale and in French.

Maps from a later 1795 edition of this work were used by Messier to show the location of his discoveries.