ABSTRACT
Of all the principles that can be proposed for this purpose, I think there is none more general, more exact, or easier to apply, than that which we have
used in this work; it consists of making the sum of the squares of the errors a minimum. By this method, a kind of equilibrium is established among the
errors which, since it prevents the extremes from dominating, is appropriate for revealing the state of the system which most nearly approaches the truth.
Two variable organs are said to be co-related when the variation of the one is accompanied on the average by more or less variation of the other, and in
