Introduction. 



xlix 



59. The maximum and minimum register thermometers are also by Adie 

 and Son. These thermometers, on Rutherford's construction, were 4 feet above 

 the ground, near the east window, facing the north, and protected from the sun's 

 rays by projecting sides of wood. Tiie roof was of copper, till August 1842, when 

 one of wooden spars, shelving to the south, was substituted, as the sun shone on the 

 copper top at rising and setting in the summer months. 



60. The thermometer of the bifilar magnetometer is by E.OSS of London, and 

 of the balance magnetometer by Robinson. 



61. The following table contains the corrections of the thermometer to a stand- 

 ard thermometer by Newman ; the comparisons being made in freezing mixtures 

 and water. 



Table 25. — Corrections of Thermometers to Newman's Standard Thermometer. 



Temperature. 



Dry. 



Wet. 



Max. 



Min. 



Bifilar. 



Balance. 

















1°6 



-0-5 



-6-5 



-0-1 



-0-2 



+ 01 



-0-2 



22 



-0-5 



-0-5 







-0-2 



-0.8 



32 



-0-6 



-0-5 



-0-1 



+ 0-1 



-01 



-0-4 



43 



-0-5 



-0-4 



-0-4 



+ 0-2 



-0-3 



-0-6 



55 



-0-4 



-0-3 



-0-4 



+ 0-3 



-0-5 



-0-4 



61 



-0-2 



-01 



-0-4 



+ 0-4 



-0-4 



-0-3 



71 



00 



+ 01 



-0-1 



+ 0-5 



-0-2 



-0-2 



80 



+ 0-1 



+ 0-2 



+ 0-1 



+ 0-5 



00 



+ 0-2 



90 



+ 0-1 



+ 0-3 







0-0 



+ 0-1 



All the readings of the thermometers in this volume have been corrected by 

 the above quantities. 



§ 10. Rain-Gauges. 



62. The rain-gauge A was placed in an inclosed space on the top of the Obser- 

 vatory hill, June 26. 1842. Its funnel mouth is 6,1 inches in diameter, 8 inches 

 above the soil, and 218 feet above the level of the sea. The quantity of rain is 

 measured by pouring it into a graduated glass tube. 



The gauge B is placed on the top of the greenhouse. The funnel mouth is 

 6.7 inches in diameter, 18 feet from the ground, 192 feet above the level of the sea, 

 and 680 feet NNE. of the gauge A. This gauge is sheltered by trees to the E. 

 and NE., and its indications are, therefore, less trustworthy, especially during E. 

 and NE. winds. The quantity of rain received is also affected by gusts of wind 

 deflected from the sloping roof. 



The daily observations for this gauge, in the month of May 1842, were lost ; 

 the sum for the month will, however, be found in the Abstract. 



In the Abstract, the monthly readings of another gauge C are given. This 



MAG. AND MET. OBS., VOL. I. n 



