XIII -THE ROOKERY MAPS OF THE PRIBILOF ISLANDS. 



By Jefferson F. Moskr, 

 Lieutenant-Commander, U, S. N. 



In the instructions of May 9, 1896, given prior to tlie detail of the Albatross to 

 assist the Fur-Seal Commission, the following work was outlined: 



The correction of inaccuracies in the shore lines of the rookery maps; the location of Mr. Town- 

 send's landmarks ; the determination of the length and width of, at least, the most important rookeries 

 by actual measurement, where this could be undertaken without disturbing the seals ; the establish- 

 ment of rookery outlines by plane-table surveys, discriminating accurately as to the limits of breeding 

 and hauling grounds as indicated by Mr. Townsend. 



In subsequent instructions of date of May 13 I was directed to determine discrep- 

 ancies between the maps of Elliott, Townsend, Stanley-Brown, and Drake, and to 

 verify the accepted ones. As these instructions were afterwards modified by a different 

 detail of the vessel, it was impossible to carry out the original orders in their entirety, 

 but I was able to ascertain what the differences in the maps are and how they may 

 be remedied. 



The Albatross was at the islands of St. George and St. Paul from July 8 to 18, 

 and when the conditions were in the least favorable not a moment was lost in making 

 observations in the field for the verification of the rookery maps. 



I was supplied with a set of the Stanley-Brown rookery maps on a scale of 264 

 feet to 1 inch. A set of the same maps showing the areas of 1895 and shore line cor- 

 rections by Drake with Townseud's criticisms, and also a set of the Elliott maps, were 

 furnished me. Before arriving at the islands a set of the Stanley-Brown maps were 

 prepared with Drake's shore line corrections in black, and. Elliott's shore line trans- 

 ferred, so far as it was possible, in blue. The Elliott shore line, as taken from the prints 

 furnished, was a bad misfit, as will be seen from the records accompanying my fuller 

 report to the Fish Commission, and it rarely stood the test of an instrumental angle. 



I desire, however, to say that the Elliott maps furnished seem to be a photo- 

 graphic enlargement to fit the scale of the Stanley-Brown maps. It is plain to be 

 seen that the enlargement of any map, even by the most expert draftsman, necessarily 

 enlarges the errors, and when enlarged by photography, unless done by special 

 appliances, and by an expert in this particular line, other errors are introduced. It 

 is hardly i'air to test a map with instruments in the field unless the original work is at 

 hand, and this holds good not only with the Elliott maps but with the Stanley -Brown 

 maps, for it is well known that the wet print in drying is very appreciably distorted. 

 I will only add that the topography of the Elliott prints as issued to me is so very 

 vague and indefinite that it is next to impossible to do anything with them; I should 

 call them sketches. 



1 had several interviews with Mr. Joseph Stanley-Brown upon the methods 

 employed in making these surveys and learn as follows: The triangulation of St. Paul 



321 

 5947— PT 3 21 



