De Tribus Cometis
- Foldout with copperplate engraving.
- Orazio Grassi (1583-1654).
- De tribus cometis anni M.DC.XVIII. Disputatio astronomica publice habita in Collegio Romano Societatis Iesu ab uno ex patribus eiusdem societatis.
- Rome: Jacopo Mascardi, 1619.
Grassi’s treatise includes an engraved foldout with numerous drawings, tables, and diagrams, mostly recording the dates and locations in which the comets were observed from various European cities. For instance, on the upper left corner, we read that the first comet was seen in Rome on August 29, 1618, under the hind foot of the Ursa Maior, as it is shown by the letter L.