Ivi Introduction to the Makeestoun 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 = — 003 inch, 

 whence 



Correction of the Makerstoun standard barometer to the standard barometers of the 



Royal Society = — 0012 inch. 



84. All the observations are corrected to the Royal Society's standard baro- 

 meter, and for temperature by Schumacher's Tables, given in the Report of the 

 Committee of Physics 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 night), 

 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 



