Thermometers. 



Ivii 



the abstracts of results, the reading of the wet bulb has been considered the same 

 as that of the dry bulb. 



91. The following Table contains the corrections of the dry and wet bulb 

 thermometer readings for 1844, to the reading of a standard thermometer by 

 Newman, — the reading of the latter, in a mixture of pounded ice and water, being 

 32°'00. On January 7, 1843, a series of comparisons of different thermometers 

 was made with the standard thermometer ; the comparisons were made in water 

 of different temperatures ; the results were given in the Introduction for 1843, 

 Table 23, p. Ivii. On October 17, 1843, the readings of the thermometers in a 

 mixture of pounded ice and water were obtained ; they were as follow : — 



Newman's standard, 32°-00. Dry bulb, 32°-8. Wet bulb, 32°-7. 



Similar comparisons, September 4, 1844, gave 



Newman's standard, 32°-00. Dry bulb, 32°-75. Wet bulb, 32°-65. 



On January 7, 1843, the readings in water and ice were, 



Newman's standard, 32°00. Dry bulb, 32°-7. Wet bulb, 32°-6. 



It appears, therefore, that in 1844, the index errors of the dry and wet bulb 

 thermometers were about one-tenth of a degree greater than in January 1843 ; 

 altering the errors, Table 23, Introduction, 1843, to this extent, we obtain the 

 following Table : — 



Table 12 — Corrections of the Dry and Wet Bulb Thermometers to the Tempera- 

 ture by Newman's Standard, in 1844. 



The observations of the di-y and wet bulb thermometers, given pages 172-308, 

 are not corrected for the errors of the thermometers ; but the corrections have been 

 applied to the abstracts of results, pages 404 — 412. 



92. The maximum and minimum self-registering thermometers, on Ruther- 

 ford's construction, were made by Adie and Son ; they were attached to a frame 

 fixed to the north side of the Observatory, about three feet from the ground, and 

 near the dry and wet bulb thermometers. A self-registering mercurial thermome- 



MET. and mag. obs. 1844. p 



