As he worked on his book through the 1830s he avidly collected and by 1841, when his work was published, he had about 1800 manuscripts including many which had previously been thought to be lost.
Bilang nagtrabaho siya sa kanyang mga libro sa pamamagitan ng 1830s siya avidly kinolekta at sa pamamagitan ng 1841, kapag ang kanyang trabaho ay na-publish, niya tungkol sa 1800 kasama ang maraming mga manuscripts na nagkaroon na dati ay nag-akala na nawala.