172 FISHING-GROUXDS OF NORTH AMERICA. 



from 1SS2 to 1SS5, inclusive, and at Mount Desert Rock, during short periods in 1881 and 18S3. 

 South of Cape Lookout, the isotherms of o'P, during the season of rising temperature, occupy very 

 different positions every year, ranging from January 1 to April 1. From Winter Quarter Shoal to 

 Fire Island, they occur mostly between the lOth and last of May, from Block Island to Nantucket 

 New South Shoal in June, and farther north in the last part of June or in July. During the 

 period of falling temperature, tliey occur in the last part of August, September, or the first part 

 of October, at Seguin Island, and in December or January on the coast of South Carolina. 



Sixty degrees. ^Thc isotherms of G0° for 1S85, are the only ones that extend northward 

 continuously to Boon Island, the isotherms of that temperature during other years generally stop- 

 ping at Nantucket New South Shoal. On the coast of South Carolina these isotherms are confined 

 to IMarch and April ; from Winter Quarter Shoal to Fire Island, Ihey occur during the last of May 

 and fust half ol' June; from Block Island to Vineyard Sound, in June; and at Nantucket New 

 South Shoal, between July 14 and August 28. During falling temperature they appear at Nan- 

 tucket New South Shoal between August 14 and October l,and reach Martin's Industry between 

 November L'G and December IS. 



Sixty-five degrees. — The isotherms of 65°, during rising temperature, occur in Ai)nl at 

 Martin's Industry and Rattlesnake Shoal, in the tirst ]iart of May at Frying Pan Shoals, but at 

 Winter Quarter Shoal not until the middle of June or first part of July. Between Five-Fathom 

 Bank and Fire Island they appear mostly in June, at Block Island in July, and at Brenton's Iteef 

 and Vineyard Sound in the last part of June and in July. During falling temperature, they occur 

 at Vineyard Sound in August; at Block Island are exceedingly variable in position, ranging from 

 Augusts to the last of September; and on the coast of South Carolina are mainly confined to the 

 month of November. 



Seventy" degrees. — The isotherms of 70° sometimes extend ro Block Island, but generally 

 terminate at Fire Island. South of Cape Hatteras they are almost entirely confined to the niontli 

 of May. From Winter Quarter Sboal northward they are exceedingly Aariable in position from 

 year to year, during the periods of both rising and falling temperature, their extreme range in 

 time in the former period being from June 18 to August IS, and in the latter from July 23 to Octo- 

 ber 14. 



Seventy-five degrees.— The isotherms of 75° are diflicnlt to plot at the Florida Reefs on 

 account of the frequent fiuctaations in temperature, which generally occur between November 

 and the following ]\lay. During those months there were often brief periods of higher tempera- 

 ture than 75°, which it was impossible to represent in connection with the isotherms, but they are 

 all shown on the .special charts of the three Florida stations. At Carysfort Reef and Fowey 

 Rocks the isotherm of 75° may appear as late as the 18th of April, durnig rising temperature, 

 and as early as the 24th of November during falling temperature. At Martin's Industry, dur- 

 ing the period of rising temperature, they occur mostly in the extreme latter part of May and at 

 Frying Pan Shoals in the first part of June. From Winter Quarter Shoal northward to Absecon, 

 these isotherms, when they appear, are mainly confined to the last part of July and August. 



Eighty degrees.— TJie iieriod of higher temperature than 80° is shorter at the Tortugas 

 than at the more northern stations of the Florida Reefs, and tlio isotherms of 80° of both series 

 bend inward ujiun the chart at that place. At Carysfort Reef and Fowey Rocks these i.sotherms. 

 on the rising temperature, were distributed, during the five years, between the lOtli and tiu' very 

 last of May; at :\Iartiii's Industry and Rattlesnake Shoal between the 12th and last of June; and 

 at Frying Pan Shoals between Hie 1st and middle of July. During the period of falling temi)era- 

 ture they occui)y a wider range in time, and extend obliquely from Fi-ying Pan Shoals to Carysfort 



