xlvii INTRODUCTION. 
TABLE 24.—Comparisons of the Makerstoun Standard Barometer with the Duke of Argyle’s 
Standard Barometer. 
Makerstoun 
Standard 
Duke of Argyle’s Makerstoun ae 
Standard. Standard. Duke of Argyle’s 
Standard. 
in. 
30-050 
29-598 
29-596 
29-176 
29-512 
29.556 
29-228 
29-450 
29-560 
The mean correction of the Makerstoun Standard Barometer to the Duke of 
Argyle’s is — 0-003, and, therefore, to the Royal Society’s — 0-012. 
From seventeen comparisons, the correction of AprE No. | to the Makerstoun 
standard is — 0-005. 
57. The observations are corrected for temperature by ScHuMACHER’s Tables, 
given in the Report of the Royal Society; those of the mountain barometer are cor- 
rected by the constant — 0-017, and of the standard, by — 0-012, the reduction to 
the Royal Society’s standard. 
The cistern is 213 feet above the level of the sea. 
§ 9. THERMOMETERS. 
58. The dry and wet bulb thermometers are by ApIE and Son. The bulbs 
are 0-3 inch in diameter, and a tenth of a degree can be estimated on the scales. 
They are placed 4 inches apart, on a wooden slab, the bulbs projecting below it. 
They were placed, from July 1841 till January 22. 1842, in the middle of a wooden 
case, the sides and tops of which were formed like Venetian blinds. 
The case was quite open below and on the side next the observatory, the 
thermometers being about 9 inches distant from the middle window, on the north 
side of the observatory ; and after January 22. 1842, from the west window on the 
same side.* This change was rendered necessary by the stove being brought to the 
middle of the observatory. 
* There is no doubt that these thermometers were placed in a bad position, being open to the 
effect of radiation from the observatory. This was, to some extent, unavoidable, as there was neither 
recess nor door on the north wall. Early in 1843, I had the thermometers placed on a revolving 
ease, which could be turned by means of cords and pulleys from within the observatory when re- 
quired, and left afterwards with a good norih exposure. 
