152 REPORT—1840. 
sedentary life ; but he whose choice or opportunity carries him 
through many climates and varying circumstances, cannot too 
zealously watch the occasion of discovering processes which 
only a happy accident may reveal, and of profiting by the com- 
parison and contrast of phenomena. Every one knows how 
indolence and indifference steal upon the mind long habituated 
to a daily-shifting scene, and how apt opportunities are to be 
lost through weariness or inattention. The traveller would do 
well, therefore, to entertain some preliminary considerations as 
to the sort of observation suited to his peculiar position. Sy- 
stematic observations are, toa great extent, beyond his reach ; 
and regular meteorological journals, kept from day to day under 
continually varying circumstances, are of much less value than 
those made in one spot, so that such registers may very gene- 
rally be abandoned, unless in the case of visiting peculiar or 
little-known climates, where any sort of approximation to sy- 
stematic observation is valuable. 
337. There are, however, certain phenomena which afford 
such definite conclusions within the range of a few or even of 
single observations, as ought especially to engage the traveller’s 
attention ; such, for instance, as 
1. The temperature of the superficial soil between the 
tropics, which, as already stated (128, note), is generally 
constant at one foot deep, and represents the annual mean. 
Intimately connected with this is the important general 
question whether the superficial earth temperature coincides 
generally with that of the air, which is yet undecided. 
2. The temperature of springs, deep wells, and mines. (117, &c.) 
The elevation of these above the sea should be determined 
barometrically or otherwise. Where several springs rise 
near one another, the temperature of severa/ should be 
recorded. It does not by any means follow, that the 
largest springs always give the best results. 
3. Particular attention should be paid to those springs which 
appear to have a temperature above or below that of the 
air at the place. In the case of very hot springs it is very 
interesting to repeat the observation with the same ther- 
mometer or instruments which have been compared, in 
different seasons and years*. (131.) 
* Having been requested some years ago to draw up instructions for obser- 
ving springs, I may, in the hope of attracting additional attention to the subject, 
introduce them here, not having been elsewhere published. 
HINTS FOR OBSERVATIONS OF THE TEMPERATURE OF HOT SPRINGS. 
The thermometer used in fixing the temperatures should be originally good, 
and should besides have its freezing point verified occasionally by plunging it in 
melting snow. Fractions of degrees should be estimated at least to one-fourth, 
