INTRODUCTION. xlix 
59. The maximum and minimum register thermometers are also by ApIE 
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. The roof was of copper, till August 1842, when 
one of wooden spars, shelying to the south, was substituted, as the sun shone on the 
copper top at risig and setting in the summer months. 
60. The thermometer of the bifilar magnetometer is by Ross of London, and 
of the balance magnetometer by Roprnson. 
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. 
16 -0-5 -0-5 —0-1 —6-2 +0-1 —0-2 
22 —0:5 —0°5 —0-2 —0:8 
32 —0-6 —0:5 -0-1 +0-1 —0-1 —0-4 
43 —0-5 —0-4 —0-4 +0-2 —0:3 -- 0-6 
55 -0-4 —0:3 —0-4 +03 —0:5 —0-4 
61 —0-2 —01 —0-4 +0-4 —0-4 —0:3 
71 0-0 +0-1 —0-1 +0-5 —0-2 —0-2 
80 +0-1 +0-2 +0-1 +0-5 0-0 +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. Rarn-GAauGEs. 
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 
