22 



RECORD AND REDUCTION 



By means of Table I, we can make the following combinations of mean tem- 

 peratures of the seasons of the year at different localities, which tabular numbers 

 and combinations may be useful in future investigations of the course of the 

 monthly isothermal lines, and of the isotherms of the several seasons. 



Year. 



North 



latitude. 



West 

 longitude. 



Mean 

 temperature. 



Corrected for 

 iudex error. 



1858 



Autumn 

 Winter 

 Spi ing 



Summer 



75°.l 

 73.0 



68.0 



74.0 



b7°.3 

 64.0 



75.0 



+ 6°.82 

 —20.59 

 +11.53 

 +35.70 



+ 6°. 74 



— 2ii.T:i 

 + 11.47 

 +35.70 



The last three (but one) columns of Table I, exhibit the observed montbly 

 maxima and minima of the temperature, and the extreme monthly range. These 

 numbers are only relative, since the absolute extremes were not found recorded. 



The highest temperature observed near Port Kennedy was +55°.0, on July 29th, 

 L859, and the lowest, — 49°.8 (the index correction having been applied), on 

 January 21st, 1859, and February 15th and 18th, 1859. Extreme range recorded 

 at the winter quarters of the "Fox," 104°. 8 of Fahrenheit's scale. To compare 

 with the above numbers, Dr. Kane recorded at Van Rensselaer Harbor a maximum 

 temperature of +51°. 0, on July 23d, 1854, and a minimum temperature of — 66°.4, 

 on February 5th, 1854, and of — 65°.5, on January 8th, 1855; observed absolute 

 range 117°.4 Fahr., exceeding the Port Kennedy range by 12°.G. 



The monthly range is greatest in March and April and in October and November; 

 its value may be set down as 52° at Port Kennedy. This range is least in Decem- 

 ber and January and in July and August, when it does not exceed 27°. The ex- 

 treme montbly range occurred in April, 1858 (viz., G4°), and in August, 1859 

 (vi/., 17°). 



Diurnal Variation of the Temperature. 



The material collected in Table II furnishes the basis for the discussion of the 

 diurnal fluctuation of the temperature. The hourly means (at certain observing 

 hours) recorded there do not present the true daily fluctuation of the temperature 

 in each month, on account of the disturbing effect of the annual change during the 

 interval of a day, an effect which cannot be neglected in a locality where the 

 annual fluctuation amounts to the excessive quantity of 79°.4. The tabular num- 

 bers, therefore, must first be cleared of this disturbing effect. This is best done by 

 computing, by means of our expression for T, the change of the annual variation 

 in a day for the middle of each month, and by correcting the means for the hours 

 A. M. and 12 P. M. by one half of this change, with opposite signs. There is no 

 correction for noon, and a proportional one for the intermediate hours between 

 morning and noon, and between noon and midnight; the signs in the second in- 

 terval being the reverse from those in the first. The diurnal fluctuation during 

 the long arctic night is so small as to be almost effaced by the overpowering effect 

 of the annual fluctuation during a day. 



C »nfir attention for the present to the diurnal variation of the tempera- 



