Even the ancient scribes who practiced their art on the Herculaneum papyri used different types of grids to delimit the writing surface. The first scientific confirmation of this habit is due to the results of the team of the ERC Advanced Grant 885222-GreekSchools project, coordinated by Graziano Ranocchia, professor of the Department of Philology, Literature and Linguistics of the University of Pisa. The project is dedicated to the analysis with advanced techniques of the carbonised papyri of Herculaneum, kept in the National Library "Vittorio Emanuele III" in Naples. The study that led to this important discovery is presented in the journal Scientific Reports, published on Nature. The publication, resulting from the collaboration of physicists, chemists and papyrologists, has highlighted for the first time the presence of various types of grids in ancient Greek book scrolls. It was already known from the classical authors that the ancient scribes used for this purpose a ruler and a lead washer, which when rubbed on the surface of the papyrus left a thin, barely visible trace, which served to indicate the margins of the text. Never before traces of it had been evinced in the numerous papyri that have come down to us from ancient times, to the point that modern scholars have puzzled over the meaning of these testimonies for decades. The scanning X-ray macro-fluorescence experiments performed on the Herculaneum papyri of the National Library of Naples by the group of Paolo Romano, researcher of the Institute of Cultural Heritage Sciences of the Cnr (Cnr-Ispc) of Catania, and of the INFN Southern National Laboratories, have provided experimental proof of the correctness of this information. Thanks to the portable instrumentation developed in Cnr-Ispc with the MUR PON IR SHINE project, different types of grids were revealed for the first time, consisting of lead lines arranged orthogonally with the clear aim of delimiting intercolumn spaces, columns, intercolumns and single writing lines.