XxX INTRODUCTION TO THE MAKERSTOUN OBSERVATIONS, 1847 To 1855. 
Jan, Feb. March April May June July Aug. Sept. Oct. Nov. Dee. 
-08 -—15 -22 -—-34 -—32 -—-35 -32 -—35 —35 -18 -10 —07 
During the years 1851 to 1855, making use of the observations sent to the “ Kelso 
Mail,” there are in all six hours, viz., 7 a.M., 9 A.M, 104.m., 1 P.m.,4 P.M., 9 P.M., 
Makerstoun mean time, and the following corrections require to be applied to the 
mean of these observations :— 
Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dee. 
210:3°) 20:9 = V21:3 © \— 2:3) — 2 = 2:4 2 = 23.) 2-3) a— 1-0 0-5 Os 
The third column contains the calculated daily means of sky clouded, being 
merely the means of the daily observations, of which (as already mentioned) there 
were five during 1847, two during 1848 and 1849 and January 1850, and four 
from February 1850 till the end of 1855. The observations communicated to the 
‘Kelso Mail” were not made use of. 
In the 4th, 5th, 6th, and 7th columns, we have the height of the barometer, 
the temperature of the air, the temperature of evaporation, and the relative 
humidity for 11 a.m. Gottingen mean time, and in the next four columns we have 
the same elements for 5 p.m. Gottingen mean time. These columns are continued 
throughout the whole series of observations. The only remark it is necessary to 
make regarding these is the following one. The relative humidity was calculated 
according to ApsJoHN’s formula, viz. :— 
2 adeh : 
y= — 97 * 30 for temperature of evaporation above 32° Fahr. 
And 
Bl OF 
f’ =f—55 en for’ |, do. below 32° ,, 
where /” is the elasticity of vapour required to be found, /’ the elasticity corre- 
sponding to the temperature of the wet thermometer, d the difference between the 
dry and wet thermometers, and f the height of the barometer. The labour of 
calculation was abridged by using a sliding-rule adapted to Apyonn’s formula 
invented by the late Mr WELSH. 
The 12th and 13th columns contain the readings of the maximum and mini- 
mum thermometers on RUTHERFORD’S principle. These observations are discon- 
tinued after August 1850. Occasionally it will be found that the reading of the 
minimum thermometer is higher than the calculated daily mean temperature, 
an instance of which occurs on December 18,1847. There are two circumstances 
which may lead to this result. 
1°. The calculated daily mean temperature, although on the average of a 
number of days coming very near the truth, may yet not represent accurately the 
average temperature of some one particular day. 
2°. The minimum thermometer is noted and reset about 10" a.m., the maxi- 

