THE HIMALAYAN MOUNTAINS. 7 
In crossing the Jumna in the latitude of Delhi, and entering the Doab or flat country 
between that river and the Ganges, a considerable difference is observed in the vegetation, 
the arid-looking thorny shrubs having disappeared, aid the trees become more luxuriant; 
tlris is consequent chiefly upon a change of soil, and is more observable as we approach 
Meerut and Saharunpore ;—if we take the latter as an example, we shall obtain a fair 
specimen of the Flora of the plains of northern India. 
- The district is flat with but slight inequalities, intersected by several rivulets and 
watered by the Doab canal. The soil is generally clayey with a proportion of sand, 
having a substratum in many places of hard and retentive brick clay, and in some 
situations kunkur, imbedded in masses sometimes large enough to be used in the erection 
of tombs, but is generally employed only for making a coarse kind of lime. Below ~ 
this, small gravel is brought up in digging wells. A part of the district is rather more 
elevated than the rest, therefore drier; and water being more distant from the surface, 
the wells are deeper; this tract is called khadir, while towards the hills and beyond 
Kheree, the eround being low, moist, and frequently overflowed, is called bangur land. 
The climate has been described as being that of India in general; but modified 
by the more northern position of Saharunpore, as the cold commences earlier, con- 
tinues later, and is succeeded by a short spring in February and March, when the 
deciduous trees come into leaf, and the greater number into flower; the heat in May 
and June is considerable, and the rains plentiful. The periods of occurrence of 
the maximum and minimum temperature (105° and 37° in June and January) being 
remote, the rise and fall very gradual and divided between several months, a degree — 
and continuance of cold weather is produced, which allows of the growth of many 
annuals apparently incompatible with the Flora of the country; while the great 
rise of temperature in the hot months, and the influence of the periodical rains, 
permit the successful cultivation of tropical plants, which appear equally at variance 
with the European-like cultivation of the cold-weather months; as the great heat, 
however, is never very long continued, nor the cold excessive, many perennials both 
of tropical and temperate climates thrive here in the open air, and this latitude 
may be considered as being nearly the northern limit of the Flora of India, as well 
as the southern boundary of that which is called the Oriental or Persian region. 
Tropical plants cannot easily extend beyond this, for though they can resist a 
- moderate degree of cold in a dry atmosphere, in the north-western provinces there 
is always a good deal of rain about Christmas, when the cold, much increased in 
consequence of the freer radiation which ensues on the clearance of the atmosphere, 
combined with the moisture, is injurious to many plants, which have besides to 
undergo great vicissitudes of temperature instead of the equality of the tropics. 
Hence in valleys and in the midst of thick forests, where the climate is moister, 
the radiation less free, and the range of the thermometer less extensive, we find the 
same plants reaching a much higher latitude than in the open plains. This we 
shall see strikingly exemplified as we pass through the belt of jungle in ascending 
tlie 
