ECOLOGY OF ISLE ROYALE. 49 



depth of 100 feet. In other localities to the southward there is a marked 

 difference between the surface and deep water temperatures. 



"In confirmation of this current there may be mentioned the follow- 

 ing special drifts, the numbers referring to those on the chart* : 

 (7) Drift of the yacht Albatross in summer, during a dead calm; papei'S 

 thrown overboard remained alongside of the yatch for several hours; 

 the drift was strong and uniform to the west. (8) Track of driftwood 

 floated by party from the boat in a calm off McCargoes Cove, Isle Eoyale. 

 (9) Drift of wreckage from the Silver Jslet crib and pier which was 

 washed away in a northeast storm. (10) Eecord of ice floes in calm 

 weather during winter of 1891 ; reported to have drifted from the north- 

 east to southwest at a rate of 3 miles an hour. (11) Drift of party in 

 sailboat while becalmed on July 31, 1894. (12) Steamer Cumberland, 

 which went to pieces ou Eock of Ages, in 1877; whose wreckage was 

 distributed along the entire south shore of Isle Boyale. (13) Drift of a 

 champagne bottle floated bv Mr. W. H. Arnold, Port Arthur, Out., on 

 October 8, 1893; and (14)" the drift of a fish barrel floated by J. H. 

 Malone, keeper Menagerie Island Light, about August 27, 1885, and 

 picked up twenty-six days later. The wind during this period was mostly 

 from the south shore. 



' "The confirmations indicate that the curi'ent between Isle Eoyale and 

 the north shore sweeps to the west and southwest after passing the 

 island and recurving rejoins the main easterly current to the south and 

 west; the drift of the wreckage from the Silver Islet pier indicates that 

 it recurves at some point to the southwest of Grand Marais, Minn. 



"Special attention is called to the current between Isle Eoyale and 



the north shore. The great depths, the conformation of the bottom, and 



the water temperatures in this locality indicate that there is a steady 



and fairly strong current sweeping from the east through the narrow 



pathway to the west, flowing to the southwest after passing the west 



end of the island, and rejoining the main easterly current as mentioned 



above. This narrow and relatively rapid stream, like the one between 



the Manitou Islands and the Michigan mainland in Lake Michigan is 



probably the most persistent and regular to be found in this lake. * * 

 # * 



"1. Section 79. — Floated by Capt. H. O. Jackson, steamer L. Shicka- 

 luna on June 23, 1893, at 6:45 p. m., in northwest corner. Found by 

 Charles Lesage, Lake Linden, Mich., at entrance of McCargoes Cove, 

 Isle Eoyale, on October 20, 1893, on the beach." 



It is thus seen that drift from the north shore of Lake Superior tepds 

 to be strained from the lake currents by the various harbors of Isle 

 Eoyale. It also suggests that north shore life might also reach Kewee- 

 naw Peninsula, but so far as known this has not been recognized. Drift 

 was observed in Tonkin Bay which had evidently come from a distance 

 and dead birds reported by Peet, as drifting into Washington Harbor, 

 probably came in part from the north shore current. The long duration 

 of these currents since the Ice Age seems very probable, and undoubtedly 

 they have had an important bearing upon the geographic origin of the Isle 

 Eoyale biota, so that they cannot receive too much emphasis. 



A few words may be added concerning the probable history of the 



* Not reproduced .on the map or figure. 

 7 



