TEMPERATURE OF THE AIR. 263 
TABLE II.—Means of the Maximum and Minimum Temperature of the Air for each Day in 1843, as 
deduced from the Self-Registering Thermometers. 
January. | February.| March. April. May. June. July. August. |September.| October. | November.) December. 
° ° ° is} ° ° o ° ° ° fo} o 
33:0 41-1 31-8 51:5 46-2 45-7 55:8 56-4 62-1 |, 59-7 35-1 34-6 
32-0 39-0 32-6 52-5 44-8 56:3 57-9 59-3 64-9 53-9 37-4 36-7 
32-8 32:3 33-9 50-2 48-3 46-2 61:3 59-7 64:3 48-5 36-6 44-2 
39-0? 29-9 30-7 44-4 50-1 45-3 56-7 59-0 56-4 56-4 44-3 48-5 
35-5 32-1 36-7 45:8 46-1 43-3 59-5 56-1 52-7 58-6 38-9 49-4 
37-5 33-0 42-4 44-7 47-2 46-8 59-8 55-5 61.6 58-7 43-1 42-3 
37-5 38-2 40-5 45:8 49-3 52-2 56-7 54-6 56-2 53-9 44-6 48-1 
31-5 40-6 32-6 41-9 45-3 54-2 57-0 63-2 58-7 48-9 37-6 45-9 
31-9 | eee 34:5 39-1 47-1 53-0 58-2 60-8 62-0 44-4 33-1 45-2 
35:3 34-7 38-1 35-1 44.4 55-8 58-9 54:5 58-7 44-8 37-1 44-4 
33-2 35:5 41-7 35-7 48-4 51-9 59-7 57-0° 62-6 40-5 43-0 47-2 
26-1 37-6 47-2 35-0 47-8 50-6 56-3 59-6 64-3 41-7 38-2 44-9 
29-2 32-9 40-0 34-2 54:0 |, 47-6 59-3 61.3 55-4 36-8 42-8 46-8 
34:8 26-9 37-8 45:3 54-6 52-0 57-8 57-0 51-6 39-4 35:8 47-1 
Peort. 23-3 38.3 50-5 45-8 56-2 60-0 56-5 61-1 34.8 37-1 50-7 
49-0 35-9 34-1 44-8 51-7 48-7 58-3 53-4 44-3 34-3 49-4 44-0 
47-5 36-0 38-2 46-4 46-0 49-6 57-9 54-6 44.7 41-9 48-9 43-7 
48-0 39-9 43-7 43-1 51-9 59-0 56-4 42-4 41-7 45:8 46-0 
47-0 38-5 49-2 47-3 53-9 57-6 52-5 55-5 32-1 39-2 45-0 
46-5 50-5 45-3 59-2 59-6 36-2 44-6 
38-7 33-4 40-5 45-6 | 47-1 51-9 57-1 | 57:8 56-2 43-9 39-6 45-1 
Annual Variation of Temperature.—The mean temperature is least for the month of February and greatest 
for the month of August; the means for April, May, and December differ little from the mean for the year. 
The monthly means differ slightly in Tables I. and II. ; one cause of this difference will evidently be found in 
the means for Sundays, included in Table IJ.; when these means are deleted, the monthly means from the 
self-registering thermometers are as follow :— 
Jan. Feb. March. April. May. June. July. August. Sept. Oct. Nov. Dec. 
39°0 33°4 40°2 45°3 46°9 52°1 57°1 57°9 55°7 48°4 39°8 44°-9 
These quantities differ from the means, Table I., from the observations of the dry bulb thermometer by 
Jan, Feb. March. April. May. June. July. August. Sept. Oct. Nov. Dee. 
Ono eh Ore elo Oy Ore 4071 2 0e3 +076 -- Orb) jello 40-2") —O3 
These differences evidently have a law, the amount being greatest near the equinoxes and least near the solstices. * 
* These differences and their variations are probably due to three causes; jirst, difference of exposure of the register and dry 
bulb thermometers ; second, difference in the form of the diurnal curve for the various months; third, less conducting power of the 
spirit of wine of the minimum thermometer than of the mercury of the maximum. From the last, the registered minimum will, in 
general, be higher than the true minimum, and so much the more when the change of temperature is most rapid, or when the diurnal 
“range is greatest, namely, near the Equinoxes. See Table III. 
