AND MOUNTAINS OF N.W. INDIA. xxxy* 
of their own latitudes,—that is, of the plains at their base,—they have the summer temperature of 
European countries; so that, without exaggeration, it might be said :— 
Gurmush nu gurm ust,— Its warmth is not heat,— 
Surdush nu surd. Its coolness is not cold.” 
The mildness of the night, compared with the coolness of the day, appears to be owing to the descent 
of strata of the atmosphere, which the heat of the day had caused to ascend. These, in descending to a 
lower station, become more condensed, and thus having their capacity for heat diminished, give out a 
portion of their latent caloric, which necessarily prevents the sinking of the temperature to the degree it 
otherwise would, in consequence of the cooling effect of radiation from the surface of the soil. Favoured as 
this process is by the stillness and clearness of the night, its effects would be more perceptible, did not 
the breadth of the ridge bear but a small proportion to the mass of the air by which it is surrounded. 
This equability of temperature is observed, not only from day to night, but also from hour to hour, and 
from summer to winter. 
One great anomaly presents itself in consequence of the still calmness of the mornings; for though 
the nights are pleasant and the mornings cool, yet, from the rapid rise of the sun, and the great power of 
the solar rays, the heat becomes considerable, and even insupportable in the open air, until a gentle 
breeze rises, and ascending up the valley, continues through the day, apparently following the course of 
the sun. The maximum of temperature frequently occurs at ten, or, at all events, the increase after 
that is so slight as not to be perceptible to the senses. In the plains we know the temperature of the air 
goes on increasing until 2 or 3 p.m. As the latitude is nearly the same as that of Saharunpore, the power of 
the solar rays and the quantity of heat communicated in a given time must be nearly the same; but in 
the plains it is allowed to accumulate: in the hills, on the contrary, the breeze which sets in daily 
from the plains towards the hills, and which commences about 10 a.m. (the very time after which so 
little increase takes place in temperature), passes over the top of the range, and prevents the accumula- 
tion of any heat. This breeze, though caused by the heat of the sun rarefying the dense air, at the sur- 
face of the earth, might be expected to arrive at the mountain top in the hot and parched state in 
which it rose from the heated plains ; but the air as it ascends becomes still less dense, and in proportion 
to this diminution of density is its capacity for heat increased ; so that it absorbs all the caloric which, 
in the plains, was sensible to the feelings, or was observed by a thermometer, and thus, on arriving at 
the top of the range, it feels cool and refreshing.* At night, a similar, but more gentle breeze, sets 
in from the hills towards the plains, and the two may, with the strictest justice, be compared to the 
land and sea breezes of the Coast and of Equatorial islands. 
As instances of the very gradual rise and fall of the thermometer from hour to hour, as well as of the 
little diminution of heat during the night, the following observations shivangecaan which were all care- 
fully made in the open air, and on clear sunny days, but in the shade :— 
Time <evess 8. Os Su Se 10 A te te EL a. 8. 9. BV. ds 48. 
April]19.... 58 — — 705 765 77 76 75 76 — 67769 — ———-— — — 60 
»» Qleeee 59 62 665 72 745 745 73-5 735 71-5 715 72 715 68 65 64 — — G25 t — 
May6...... 53:5 585 63 68 75 75 755 76 755 72 66°70 69 — 64 — — 5B — — 
* Cloudy. + 57-55 next morning: + 56 next morning, at day-break. 
The transition to the rainy season is not accompanied with so great a diminution of temperature as ae 
might be expected. In the year 1829, the rains came on on the 15th of June. The mean temperature : = 
of the two previous days was 67° and 68°, while that of the twenty-four hours subsequent to the Bec roe 
was 62°, and that of the whole day of the 16th was 63:5. 
* These observations were first published by the Author in a Paper read before the Asiatic oe of Caleutta, and. xt 
lished in the Journ. As, Soc., vol. i, p, 97. oe 
