ALASKA INDUSTRIES. 333 



ground evenly, never crowding in at one place here to scatter out there. 

 The seals lie just as thickly together where the rookery is boundless 

 in its eligible area to their rear and unoccupied by them, as they do 

 in the little strij)S winch are abruptly cut off and narrowed by rocky 

 walls behind. For instance, on a narrow rod of ground under the face 

 of bluffs which hem it back as land from the sea there are Just as many 

 .seals, no more and no less, as will be found on any other rod of rookery 

 ground throughout the whole list, great and small; always exactly so 

 many seals, imder any and all circumstances, to a given area of breeding 

 ground. There are just as many cows, bulls, and pups on a square rod 

 at Nah Speel, near the village, where, in 1874, all told, there were only 

 7,000 or 8,000, as there are on any square rod at Northeast Point, 

 where a million of them congregate. 



"This fact being determined, it is evident that just in proportion as 

 the breeding grounds of the fur seal on these islands expand or contract in 

 area from their present dimensions the seals will increase or diminish in 

 number. 



"My discovery, at the close of the season of 1872, of this law of dis- 

 tribution, gave me at once the clue I was searching for in order to take 

 steps by which I could arrive at a sound conclusion as to the entire 

 number of seals herding on the island. 



"I noticed, and time has confirmed my observation, that the period for 

 taking these boundaries of the rookeries so as to show this exact margin 

 of expansion at the week of its greatest volume, or when they are as 

 full as they are to be for the season, is between the 10th and 20th of 

 July of every year — not a day earlier, and not many days later. After 

 the 20th of July the regular system of compact, even organization 

 breaks up. The seals then scatter out in pods or clusters, the pups 

 leading the way, straying far back — the same number instantly covering 

 twice and thrice as much ground as they did the day or week before, 

 when they lay in solid masses and were marshaled on the rookery 

 ground proper. 



"There is no more difficulty in surveying these seal margins during 

 this week or ten days in July than there is in drawing sights along and 

 around the curbs of a stone fence surrounding a field. The breeding 

 seals remain perfectly quiet under your eyes all over the rookery, and 

 almost within your touch, everywhere on the outside of their territory 

 that you may stand or walk. The margins of massed life, as I have 

 indicated on the topographical surveys of these breeding grounds of 

 St. Paul and St. George, are as clean cut and as well defined against 

 the soil and vegetation as is the shading on my maps. There is not the 

 least difficulty in making the surveys, and in making them correctly. 



"Now, with a knowledge of the superficial area of these breeding 

 grounds, the way is clearly open to a very interesting calculation as to 

 the number of fur seals upon them. I am well aware of the fact when 

 1 enter upon this discussion that I can not claim perfect accuracy: but, 

 as shadowing my plan of thought and method of computation, 1 propose 

 to present every step in the processes which have guided me to the 

 result. 



ROOKERY SPACE OCCUPIED BY SINGLE SEALS. 



" When the adult males and females, fifteen or twenty of the latter to 

 every one of the former, have arrived upon the rookery, I think an area 

 a little less than 2 feet square for each female may be considered as the 

 superficial space required by each animal with regard to its size and in 



