Prof. Blasius on the Ornithology of Heligoland. 6 1 



He was led to the island by his art, and became a collector and 

 observer of ornithology merely by chance. This chance offered 

 itself to him in the shape of a Norwegian Gyrfalcon killed in 

 Heligoland. In a countiy where only Sparrows and Loons 

 breed, the appearance of a noble Falcon was quite a phenome- 

 non. Gaetke was sorry to leave this beautiful bird to decay, 

 and made an attempt to stuff it as well as he was able. It 

 forms the still-preserved nucleus of his collection ; to which in 

 the progress of time, and little by little, all other specimens that 

 seemed to him of some importance were added. Finally he con- 

 ceived the idea of collecting examples of all the species killed on 

 the island, and has now succeeded in obtaining in this narrow 

 space more than 400 out of about 500 known European 

 species. In his endeavours to attain this result he was assisted 

 by many of the indigenous inhabitants, fishers and gunners, and 

 especially by the brothers Aeuckens. Gaetke kept from the 

 beginning a diary of all the rarer species. The time, the spot, 

 and the circumstances accompanying the killing of each bird are 

 carefully registered, together with his observations. Besides, 

 the diary contains special measurements — a process which can 

 be performed only with fresh-killed birds, with flesh and tissues 

 still existing, by means of stretching them in a peculiar manner 

 on paper. The colours of the several parts, which are commonly 

 changed or lost by preparation, are fully detailed. Even the 

 voice, the posture, and the movement of the living birds are not 

 forgotten in his notices. Every one who is at all acquainted with 

 practical ornithology must be convinced by a glance at these, that 

 there cannot have been the slightest attempt at deception ; every 

 one will recognize in them the evidence of a conscientious and 

 careful observer. He who looks over the contents and the 

 progress of this diary, and compares the text of the later with 

 that of the previous years, will cast aside all idea of dishonesty 

 with contempt. For my part, I hope that not one of the obser- 

 vations recorded in this diary may be lost to European orni- 

 thology. 



The collection itself corresponds perfectly with the text and 

 contents of this diary. Each individual belonging to a rare 

 species is, without exception, still preserved in the collection. 



