lii Introduction to the Makerstoun Observations, 1845 and 1846. 



Barometer. 



85. The barometer is by Newman. The tube is 0-552 inch in diameter; the 

 scale is attached to a brass rod, terminating in an ivory point, which at each ob- 

 servation is moved by means of an endless screw till it meets its image in the mer- 

 cury of the cistern ; the cistern is about 3 inches in diameter ; the vernier professes 

 to read to 0*002 inch, and that 0*001 inch may be estimated, but the graduation is 

 so inexact as to give changes in error from 0'002 to 0*003 inch, when the reading is 

 made alternately at the two extremities of the vernier. 



86, In 1841, the barometer was compared indirectly with the standard baro- 

 meters of the Royal Society of London, by means of one made by Newman for the 

 Duke of Argyle. The comparisons of the Duke of Argyle's barometer with the 

 readings from the flint and crown glass tubes of the Royal Society (both tubes being 

 connected with the same cistern) are given. Table 23, Introduction, 1841-2. They 

 are not consistent. A consistent series of comparisons of the Makerstoun barometer 

 with the Duke of Argyle's is given. Table 24, Introduction, 1841-2. The results 

 of these comparisons are 



in. 



D[JKE of Argyle's barometer minus Royal Society's crown and flint glass, = + 0009 

 Makerstoun barometer minus DuKE of Argyle's, =4- 0003 



Makerstoun barometer minus Royal Society's crown and flint glass, 



= + 0012 



87. In July 1847, a series of comparisons was made by myself of a barometer 

 by Troughton, marked B, belonging to Sir Thoivias Brisbane, with the flint-glass 

 barometer of the Royal Society of London. The same barometer (Troughton B) 

 was a few days afterwards compared by myself with the Makerstoun standard baro- 

 meter : these comparisons are given. Tables 10 and 11. 



Table 9. — Comparisons of the Barometer Troughton " B " with the Flint-Glass 

 Standard Barometer of the Royal Society of London, July 2, 1847. 



Royal Society's 

 Flint-Glass Standard. 



Troughton " B." 



Royal Society 



Standard 



minus 



Troughton "B." 



Height. 



Tempera- 

 ture. 



Height. 



Tempera- 

 ture. 



Corrected to 

 Temp, of 



Royal Society 

 Standard. 



in. 



30-302 

 •304 

 •300 

 •291 

 •292 

 •268 



63-6 

 63-9 

 64-2 

 64-8 

 64-8 

 64^5 



30-262 

 •267 

 •266 

 •254 

 •255 

 •232 



66^0 

 66-4 

 66-8 

 65-8 

 66-2 

 65-7 



in. 



30-256 

 •261 

 •259 

 •251 

 •251 

 •229 



in. 



+ 0046 

 •043 

 •041 

 •040 

 •041 

 •039 



