50 RECORD AND DISCUSSION OF TEMPERATURES. 



READINGS OF THE BLACK BULB THERMOMETER AND CORRESPONDING NOTES ON THE SOLAR LIGHT 



Continued and completed. 



Sept. 12. AtG 1 -, 7,8,9, 10,11,12, 1,2,3, 4, 5 h : B. B. +6, 12, 18, 21, 23, 21, 19, 18, 16, 14, 13, 8 



S. L. 3, ..,.., 1, 1, 1, 1, 1, 1, 1, 1, 2 



Sept. 13. Same hours : B. B. -f 2, 1, 20, 33, 31, 31, 33, 34, 28, . . , 19, 16 



S. L. 1, 1, 1, 1, 1, 1, 1, 1, 1,.., 1, 1 



Sept. 14 and 15. No. observations. 



Sept. 1C. At 8 A.M., 1, 2, 3 P.M.: B. B. +13, 16, 17, 14; S. L. 1, 1, 1, 1 



Sept. 17. At 1, 2, 4, 5 P. M. : B. B. +19, 16, 13, 9; S. L. 1, 1, 1, 2 



Sept. 18. No observations. 



Sept. 19. At 11 and 12 A.M. : B. B. +11, 13 ; S. L. 1, 1 



Sept. 20. At 11 A. M. and 3 and 4 P. M. : B. B. +9, 45, 5 ; S. L. 1, 3, 3 



Sept. 21. At 9, 10, 12 A.M.: B. B. +8, 11, 18; S. L. 1, 1, 1 



Sept. 22. At 12, 1, 2 P. M. : B. B. +20, 16, 12; S. L. 1, 2, 3 



Sept. 23. At 10, 11, 12 A. M. : B. B. -f 2, 6.5, 5; S. L. 3, 1, 1 



Sept. 24, 25, 26. No observations. 



Sept. 27. At 10, 11, 12 A. M. : B. B. +13, 13, 10; S. L. 1, 1, 2 



Sept. 28. At 11 A.M.: B. B. +13; S. L. 2 



Sept. 29, 30, Oct. 1, to 14. No observations of the black bulb thermometer. 



Oct. ]5. At 11 and 12 A.M.: B. B. 3, 4; S. L. 1, 1 



The black bulb readings were discontinued on Oct. 18. 



Decrease of Temperature ivilh Elevation. Readings of the temperature at the 

 level of the sea, and at eighty feet elevation on the mast of the brig, were taken 

 during the months of August, September, and October, 1853. These observations 

 were made with the same thermometer at the upper and lower position. The 

 following are the mean differences obtained from twelve observations (bi-hourly) a 

 day for the months August, September, and October, in the two positions : 0.14, 

 0.67, and 0.30, the minus sign indicating &quot;colder above.&quot; We have, there 

 fore, for an elevation of eighty feet, an average change of 0.37 of temperature 

 during these three months; or the elevation corresponding to a decrease of tem 

 perature of 1 Fahr. becomes 210 feet. 



/Surface Temperature of Sea Water. The following table contains the mean 

 monthly values, from hourly observations, of the temperature of the surface water 

 in Van Rensselaer Harbor. On the 19th of October, 1854, an order was given to 

 iramerge the thermometer four feet below the surface. On the previous day, the 

 water alongside gave at the surface 32; at three feet deep, 30. 5. After Novem 

 ber 27th, the readings remaining constant at +29, the observations were dis 

 continued. 



1853 September . . 29. 1 

 October . . .28.8 

 November . . .28.7 

 December . . .28.7 



1854 January . . .28.7 

 February . .28.7 

 March . .28.7 

 April . . 28.8 



1854 May .... 28. 9 



June . . . .30.3 



July . . . .32.3 



August . . . 31.8 



September . . .31.3 



October . . .30.9 



November . . . 29.0 



December . . . 



The index error of thermometer is not known ; it must be small. 



For a preliminary project of the isothermal lines of Baffin s Bay and adjacent 

 islands, constructed for each month of the year, the reader is referred to Appendix 

 No. XIII. of the 2d Vol. of the Narrative. 



