326 WORKS PUBLISHED IN 1809-10. 



The second volume of the "Equinoctial Plants" was 

 published in 1809. 



This, and the two following years, found Humboldt 

 hard at work. He had not yet decided, it would seem, 

 upon writing a regular narrative of his travels, or, 

 deciding, had postponed it for a few years longer, until 

 he could see his way more clear before him. lie would 

 first work up some of his lighter materials. His port- 

 folio was full of sketches ; his journals were overflowing 

 with astronomical observations. He entrusted the latter 

 to Oltmans, a young geometrician of Berlin, who revised 

 them and made all the calculations anew r , employing the 

 lunar tables of Berg, and correcting them at the same 

 time by the passage of the moon over the meridian. 

 The Institute of France recognised the seven hundred 

 positions calculated in this manner as the greatest mass 

 of materials for astronomical geography then existing, 

 and awarded to Oltmans, in 1809, the prize for astro- 

 nomy. His work, " A Collection of Astronomical Ob- 

 servations, Trigonometric Operations, and Barometric 

 Measurements," was published in 1810, in two quarto 

 volumes. Humboldt's own publication this year was 

 the "Picturesque Atlas." This was another of his great 

 folios, and undoubtedly the most attractive one to general 

 readers. It is not scientific, like the " Equinoctial Plants,' 

 and his other botanical works in folio, but descriptive 

 and historical — a sort of sketch-book of the New World. 

 It is illustrated by sixty-nine engravings, executed by 

 the best artists in Paris, Rome, and Berlin — such men as 

 Gmelin, Wachsmann, Pinelli, and Massard, the elder. 

 Many of these engravings were made from Humboldt's 

 own sketches, which were taken on the spots represented. 



