Abstract
The National Library of Spain, the Library of the Royal Palace of Madrid, The British Library, The New York Public Library, etc., are the background of the auth or's investigations on Spanish, European and North American lands, which were rewarded with the discovery of valuable manuscripts of great interest for the studious of the new Hispanic Mexico. The material found in those repositories includes a wide variety of different themes: from the unpublished manuscript Observationes artium diversarum..., which gives us a view of the sciences in the middle I 7th century in Mexico, to works related with Sor Juana Inés de la Cruz and the polygraph Carlos de Sigüenza y Góngora, in addition with other curious and interesting scripts on poetry, literary contests, sermons, rhetoric and other affairs.