IN METEOROLOGICAL REGISTRATION. 85 
to the retention of the present unsatisfactory mode of 
treating the subject of meteorology. But it should be 
borne in mind that the middle of the day is the time at 
which the sun exerts its power to send vapour into the 
higher regions, and that at the same time the surface is 
heated. Yet the heat which is expended in raising the tem- 
perature of the surface is evidently not the same that has 
ascended in vapour to the upper atmosphere; and as the 
latter portion of heat produces the effects we are tracing, 
we should endeavour to follow zt, and discover its particu- 
lar mode of acting. Tc do this it may be necessary to 
point out, in the best way we can, in the present state of 
meteorology, the separate action of the solar heat on dry 
ground, and on the water which is spread so extensively 
over the earth. 
In places where there is little or no water to be con- 
verted into vapour, such as dry sandy deserts, it is well 
known that the summer sun greatly raises the tempera- 
ture of the land every day. Even on the sea coast of 
Lancashire in the summer I have observed that in the 
middle of the day, while the air over the moist sand of the 
shore was at 60° the sand itself was at 75°, and the dry sand 
among the contiguous hills was at 90°. In this case an 
equal direct supply of solar heat raised the dry sand 15° 
above that which was moist; but this difference was a 
consequence of much of the solar heat that reached the 
ground passing away in vapour from the moist portion. 
A hygrometer, held in the air at the time, showed that 
vapour was ascending from the moist shore in great 
abundance. In dry countries, far from the sea, as less 
water exists to receive the heat, less vapour is daily raised 
by the sun, and therefore the temperature of the surface is 
raised to a higher degree. Burns, when near Bokhara, 
says: ‘The heat of the sand rose to 150° and of the atmo- 
sphere to 100°;” but then no water was present in the 
