after two years study of geometry" and were here inserted only to save them from oblivion.
But it was not the intention of Galileo that the Dialogues on the New Sciences should contain only the four Days and the above-mentioned appendix which constitute the Leyden Edition; while, on the one hand, the Elzevirs were hastening the printing and striving to complete it at the earliest possible date, Galileo, on the other hand, kept on speaking of another Day, besides the four, thus embarrassing and perplexing the printers. From the correspondence which went on between author and publisher, it appears that this Fifth Day was to have treated "of the force of percussion and the use of the catenary"; but as the typographical work approached completion, the printer became anxious for the book to issue from the press without further delay; and thus it came to pass that the Discorsi e Dimostrazioni appeared containing only the four Days and the Appendix, in spite of the fact that in April, 1638, Galileo had plunged more deeply than ever "into the profound question of percussion" and "had almost reached a complete solution."
The "New Sciences" now appear in an edition following the text which I, after the most careful and devoted study, determined upon for the National Edition. It appears also in that language in which, above all others, I have desired to see it. In this translation, the last and ripest work of the great philosopher makes its first appearance in the New World: if toward this important result I may hope to have contributed in some measure I shall feel amply rewarded for having given to this field of research the best years of my life.
Antonio Favaro.
27th of October, 1913.
