322 THE FUR SEALS OF THE PRIBILOF ISLANDS. 



ou the general map of the islands, scale 1:60,000, was done by Dr. Thomas 0. Menden- 

 hall in 1891, when he served as one of the American commissioners iu the investigation 

 of the fur seals. The topography was supplied by Mr. Stanley-Brown. Dr. Meuden- 

 hall was on St. Paul from July 29 to August 9, and during that time investigated the 

 seal question, made observations for gravity, and did the triangulation. A base was 

 measured on the east side of the Lagoon with an ordinary steel tape, and, from wLat 

 I can learn, no pressure balances were used and no corrections for temperature or 

 curvature were applied, and no signals were erected. I should call this triangulation 

 a reconuoissauce, and think Dr. Mendenhall claims no more for it. Tlie topography by 

 Mr. Stanley-Brown was filled in by methods which I will refer to later. The survey 

 of St. George on the general chart, scale 1:60,000, was the work of Mr. Stanley- 

 Brown. 



The rookery surveys, scale 1 inch to 264 feet, were made with a plane table 

 according to Geological Survey methods, and are entirely independent of those pre- 

 viously mentioned. Bach sheet stands by itself; that is, each rookery is a separate 

 survey and the rookeries on the different sheets were not connected. The bases were 

 measured with an ordinary steel tape and no corrections were made nor pressure 

 balances used. The azimuths were observed by means of a compass attached to an 

 ordinary geologist's clinometer. Oairns were built of loose rock at prominent points 

 and flags placed in favorable positions for observation points. No regular signals 

 were built, nor were angles observed nor computations made. The plane table was 

 placed over each end of the base successively and different points cut in, after which 

 these points were occupied and others made. JSTo high or low water line was observed; 

 the water line was cut in at the height it happened to be when the observations were 

 made. The contours were traced with an aneroid barometer. The scale of the original 

 sheets is the same as that published — 1 inch to 264 feet, or 20 inches to the statute 

 mile. 



We tested these maps as thoroughly as our limited time would permit. The 

 sheets accompanying the fuller report will show the large number of angles observed, 

 and the data, though more or less incomplete, is sufficient to show thoroughly what 

 has been done in the past and what is required for the present and future. I do not 

 think Mr. Stanley-Brown claims great accuracy for his maps. I should call them a 

 fair reconuoissauce. They are not accurate in the sense of a finished survey; they 

 lack detail, and what is given is in most instances badly represented and indefinite; 

 the lines and symbols leave one constantly in doubt as to what is' intended to be 

 understood. Yet, considering the means employed, the facilities, and the methods, it 

 is surprising to me that they are as good as they are. These surveys by Mr. Stanley- 

 Brown are no doubt the very best for these islands that have ever been made, and he 

 deserves nothing but praise in carrying out the work under the many trying conditions. 



When the rookeries were so full of seals that a few tens of thousands, more or 

 less, was a matter of no importance, these maps served their purpose and served it 

 well; they were a good general guide. They satisfied the demands at the time they 

 were made, but as the number of seals have been so much reduced and it is necessary 

 to make an estimate within small limits, we are unable with these maps to make an 

 eye survey of the areas occupied by the herd. 



The present need requires a topographical map of the rookeries so accurate and 

 in such detail that a person from an accessible position and commanding the rookeries 



