The contents of the volume are as follows:

(i) Manuscript, apparently autograph, of ‘Meteorologicae Peripateticae adversus Aristotelem Liber singularis’ by Constantyn Huygens, 1636, printed in his ‘Momenta Desultoria’, 2nd edition, pages 119-131, and in ‘De Gedichten van Constantijn Huygens’, edited by J A Worp, volume 3, pages 15-26. This manuscript stands between ‘Momenta Desultoria’ and the manuscripts used by Worp; details of the variants have been placed before the manuscript. Aesthetic comments (such as ‘bonum’, ‘ingeniosum’, ‘optinum’, ‘ά̓ριστον’) occur in the margins at all the sections. (Folio 1.)

(ii) Letter of Jos. Cabaliarius to Huygens, 1639, on the establishment of a Chair of Roman History at Amsterdam (folio 10); and laudatory letters and poems, mostly in Latin, with a few in Dutch, to Huygens from Jacobus Golius, 1630 (folio 12); Robertus Keuchenius, 1660-1661 (folio 14); Daniel Georg Morhof, 1661, 1671, 1680, 1684 (folio 27); Theodor Rycke, 1679 (folio 39); Johan Ryder, 1632 (folio 47); Johan Smith, 1633-1634, 1644 (folio 49); Johan Smith filius, 1660 (folio 61), and Gervase Warmestry, 1627. (Folio 63.)