Biographical Memoir of the late Friedrich Hoffmann. 7 



and who were fixed at home, to compare the geognostical rela- 

 tions of their neighbourhood with those of remote quarters, he 

 followed perseveringly the boundaries of the rocks, and at first 

 bestowed but an inferior degree of attention on the internal 

 structure of the formations. In order that he might not in any 

 instance pass over the connection, even of the apparently most 

 trifling geognostical relations, he combined in the year 1822 

 his observations on the Weser country with those of the first 

 year ; he also made an expedition to the isolated gypsum hills 

 of Liineberg and Segeberg, and another to the island of Heli- 

 goland, a spot so interesting in many respects, and whose 

 geognostical relations were previously quite unknown. In the 

 course of the following year he directed his attention to the dis» 

 tricts lying south-west from the Hartz, and formed a map of the 

 western boundaries of the high plain of Thuringia, the copper- 

 slate mountains of Riegelsdorf, and the neighbourhood of the 

 Meissner. 



In the mean time, the investigations of Hoffmann in the 

 hilly land lying to the north of the Hartz, had attracted the 

 notice of Leopold von Buch, and as an honourable proof of the 

 value of our author'^s first work, it may be mentioned that its 

 publication was caused by the influence of that celebrated geo- 

 logist. 



That portion of the ministry to which the direction of pub- 

 lic instruction in the Prussian States is intrusted, was now at- 

 tracted by the investigations of Hoffmann, investigations which 

 had also elicited the approbation of Alexander von Humboldt ; 

 and he was received as a private lecturer in the University of 

 Halle. The circle of his hearers was but small, as few studentfl 

 had leisure enough to permit their acquiring knowledge which 

 did not tend directly to their advancement in their particular 

 professions ; but nevertheless this circle increased gradually, 

 and was characterised by great zeal and enthusiasm. The con- 

 sequence was his speedy appointment as extraordinary professor 

 at Halle. 



But while occupied with his duties as teacher, the examina- 

 tion of the geognostical relations of north-western Germany 

 was still his chief scientific occupation. Each year he employed 

 the long summer vacation in examining thoroughly that tract 



