218 



RECORD AND RESULTS OF 



about 41 A. M. At Port Foiilke the secondary maximum and minimum occur 

 about 8 and 10| A. M. : diurnal range 0.017 inch. 



Annual Fhictuation of the Atmospheric Pressure. 

 The monthly mean values derived from the hours 8 A. M. to 10 P. M., which 

 are strictly comparable, inter se, are as follows : — 



September 



. 29.'"686 



March 



. 29'".818 



October . 



. 29.620 



April 



. 30.060 



November 



. 30.089 



May 



. 29.987 



December 



. 30.034 



June 



. 29.680 



January . 



. 29.836 



July 



. 29.693 



February . 



. 29.149 



August . 



. 29.664 



The mean of these values is 29'°.826, but the annual mean from 12 values a day 

 was 29.824; we subtract therefore 0'".002 which gives the following monthly mean 

 barometric pressure, and the annual fluctuation proper, 4- indicating greater, — less 

 pressure than the mean amount. 





All 



nual fluctuation of the atmospheric 

 Maximum marked by a *. 



pressure. 







Port Foulke. 



Port Foulke. 



Van Rensselaer. 



Port Kennedy. 



Baffin Bay. 



January 



29'".834 



+ 0i°.010 



+ 0'".003 



+ 0'".041 



— 0"'.223 



February 



29.141 



—0.011 



+ 0,013 



—0.005 



—0.106 



March 



29.816 



—0.008 



—0,025 



+ 0.235 



+ 0.138 



April 



30.058 



+ 0.234* 



+ 0,128 



+ 0.241* 



+ 0.185 



May 



29.985 



+ 0,161 



+ 0,1 CI* 



+ 0.012 



+ 0.259* 



June 



29.618 



—0.146 



—0 056 



—0,025 



+ 0.062 



July 



29.691 



—0.133 



—0.034 



—0.234 



—0.002 



August 



29,662 



—0.162 



—O.OSl 



—0.191 



—0.019 



September 



29.684 



—0.140 



—0.111 



—0.039 



—0.020 



October 



29.618 



—0.206 



—0.020 



—0.140 



+ 0.001 



November 



30.081 



+ 0.263* 



—0.011 



+ 0.114 



—0.090 



December 



30.032 



+ 0.208 



—0.022 



—0,066 



—0.185 



The true maximum occurs evidently in April, that of November being accidental. 

 The spring maximum (April and May) is well marked for either locality. The 

 mininuun at Port Foulke occurred in October ; at Van Rensselaer Harbor in Sep- 

 tember. Computed annual range at Port Foulke 0.40 inch ; at Van Rensselaer 

 Harbor 0.21 inch. 



We have also the annual fluctuation at 



Port Foulke, B = 0".120 sin (e + 48°) + 0'M41 sin (2fl + 111°) 



Van Rensselaer Harbor, B = 0.019 sin (e + 4 ) + 0.044 si7i (29 + 294 ) 



Port Kennedy, B = 0.131 sin (0 + 11 ) + 0.106 si7i (29 + 232 ) 



Baffin Bay,- B = 0.155 sin (e + 304 ) + 0.113 sin (29 + 236 ) 



The angle 6 counts from January 1st at the rate of 30° a month. 



The formula for Port Foulke places a maximum about the commencement of 

 May, and a minimum about the end of August ; it reqiures, however, more than one 

 year's observation to secure a reliable value of the annual fluctuation. 



The annual range is twenty times greater than the diurnal range. 



