lvi INTRODUCTION TO THE MAKERSTOUN OBSERVATIONS, 1843. 
A consistent series of comparisons of the Makerstoun standard with the DUKE 
of ARGYLE’s standard, given Table 24, Introduction, 1841-2, gives the mean - 
Correction of the Makerstoun standard barometer to the standard belonging to the 
Duke of ARGYLE = — 0-003 inch. 
whence 
Correction of the Makerstoun standard barometer to the standard barometers of the 
Royal Society = — 0:012 inch. 
84. All the observations are corrected to the Royal Society’s standard baro- 
meter, and for temperature by ScuuMAcHER’s Tables, given in the Report of the 
Committee of Physies of the Royal Society. 
The cistern of the barometer is 213 feet above the mean level of the sea at 
Berwick-upon-Tweed. (See No. 1.) 
§ 10. THERMOMETERS. 
85. The dry and wet bulb thermometers are by ADIE and Son. The bulbs 
are 0-3 inch in diameter, and tenths of a degree can be estimated on the scales ; 
they are placed four inches apart on a wooden slab, the bulbs projecting below it. 
The slab was placed in the middle of a wooden case, the sides and top of which were 
formed like Venetian blinds, the case was open below and on the side next the 
Observatory ; the thermometers, which were read from within, were about 9 inches 
distant from the west window on the north side of the building. As the thermome- 
ters were subject to the effect of radiation from the interior of the Observatory, the 
slab carrying them was, after January 24. 1843, fixed to the front of a wooden case 
with a slightly projecting top and sides, and with a double sloping back, the ther- 
mometers being 4 feet from the ground; the case revolves on a post, and can be 
turned from within the Observatory by means of cords and pulleys. When an ob- 
servation is made, the case is turned till the thermometers face the window, being 
9 inches distant from it ; after reading, which is done through the glass (thus avoid- 
ing any source of error due to the proximity of the observer, or the light at might), 
the case is again turned till the thermometers face the west if the sun shine in the 
morning, the east if it shine in the evening, and the north at all other times, unless 
it rain, when the back of the case is turned to the wind, if any. Holes were cut in 
the front of the case immediately behind the bulbs of the thermometers, in order to 
give a free circulation to the air around them, and to prevent any effect from the 
different temperature of the wood; a small projecting ledge below carries the cis- 
tern of the wet bulb, and prevents, to some extent, the effect of radiation from the 
soil on the thermometers. It was found, early in the summer of 1843, that, in spite 
of all precautions, when the sun shines strongly before 7 A.M., or after 5 P.M., the 
thermometers are visibly affected by it. A moveable front, to which the thermome- 
ter slab was attached, was accordingly placed on the case, and, in the morning or 
