AT NIGHT, FROM THE EARTH, ETC. 
215 
INDEX. 
Introduction. Page 
Preliminary experiments upon thermometers 120 
Description of the thermometers used in the experiments 121 
Method of comparing the thermometers 122 
Comparison of thermometers 123 
Description of the place of observation 124 
Position of the thermometers placed upon different substances, or in different positions, and! ^ \ \or 
extent of surface of the metallic plates and substances in powder / 
Precautions used in making the observations 125 
Remarks upon the tendency of bodies to become cold upon exposure to a cloudless sky at night 126 
Remarks upon the formation of dew 126 
Section I — Simultaneous observations by Mercurial Thermometers 127 
Method of reducing the observations 127 
Arranged individual results from observations forming Tables I. to XXVIII 128 to 141 
Remarks upon experiments by interposing substances between an exposed body and the sky 142 
Remarks upon the effect of covering plants at night, and interposing substances between them and"! 
the sky J 
True temperature of the air as deduced from the readings of thermometers at 13 feet above the soil. 142 
Arranged individual results from observations forming Tables XXIX. to XLIV 142 to 144 
Remarks upon Tables I. to XLIV 145 
The greatest observed difference between the readings of two thermometers placed near each other! 
during the experiments / 
Table XLV. — Mean results for each substance derived from all the observations 147 and 148 
Remarks upon the preceding Table 148 
Results relating to long and short grass 149 
Results deduced from covering grass by different substances 150 
Difference of reading of thermometers at different distances from the earth 151 
Dew remaining on grass throughout the day 151 and 152 
Formulae for correcting the readings of thermometers according to the amount of sky to which their! ^ 
bulbs are exposed / 
Remarks upon placing thermometers 153 
Results deduced from skins and filamentous substances 153 
Results deduced from wadding, flannel, coloured wools, &c 154 
Results deduced from black-lead, charcoal, whiting, lamp-black, and river-sand 155 
Results deduced from building materials 155 
Results deduced from metals 155 
Results deduced from garden mould, gravel, saw-dust and paper 156 
Table XLVI. — Amount of heat, &c. conducted from one inch beneath the soil to the surface, &c. ... 157 
Remarks on the preceding Table 158 
Remarks upon the unfitness of the preceding substances for the construction of hygrometers 159 
Table XLVII Simultaneous observations for special purposes 160 
Table XLVIII Abstract of preceding Table 1 6 1 
Remarks upon Table XLVIII l6l 
Tables XLIX. and L. — Experiments connected with snow 162 
Remarks upon the preceding Tables 163 
