It has been suggested that Gauss used the method of least squares on a data set published in 1799. The data set and its adjustment are reexamined, and it is concluded that the result of Gauss cannot be obtained by the least-squares method nor by any other approach mentioned by Gauss.
"The method of Gauss in 1799." Statist. Sci. 13 (2) 123 - 135, May 1998. https://doi.org/10.1214/ss/1028905931