The "cobweb theorem" or "cobweb diagram" is one of the first mathematical formalization that deals with the stability of the market process (Ezekiel [1938]). Moore gave intuitively its first formulation (Stigler [1962]), but its mathematical formalization was independently done by Ricci [1930], Schultz [1930] and Tinbergen [1930]. First, the paper shows how the idea of the cobweb mechanism appears in Moore's work in order to solve a statistical problem, namely the statistical estimation of supply and demand curves. "Inadvertently" (Samuelson [1947]) Moore sets out the cobweb idea which mathematical formalization was given by Ricci, Schultz and Tinbergen. Second, this paper is an attempt to trace the links between Moore's work and its followers. It shows that the meaning of the cobweb diagram was different in the authors' thought. It also stress the role of the mathematics in the investigation process of economic phenomena.