On the N.W. frontier of British India, includ ing the southern half of the Panjab and all Sind, there is an arid region, where the normal annual rainfall is less than 15 inches, and irrigation is indispensable to cultivation. It embraces the area between lat. 23° and 33° N., and from the mountains of Baluchistan in long. 60° across the Indian desert to near Lahore on the north, Dehli in the east, also Ajmir, the Aravalli mountains, and the Runn of Cutch on the south. On the N.E., E,, and S.E. of that arid region is a belt of scant rainfall from 100 to 200 milot wide, einbraeing the Sakti Koh (14 in.), Lahore (1G in.), Dellli (24 in.), Agm (27 in.), Ajmir (18 in.), rind Kattyawar, on which between 15 and 30 inches annually fall. And farther south, in the interior of the Peninsula, in the elevated traet from 1200 to 2400 feet above the sea, between the Eastern and Western Ghats, at a distance from the two seas, end extending from Nasik on the north to Cape Comorin, is a dry region with a rainfall of from 20 to 30 inches, embracing Bellary (22 in.), Bangalore 035 in.), Palameotta (22 in.).
Along the upper part of the valley of the Ganges. in Central India, and on the eastern coast of the Peninsula, the rainfall ranges from 30 to GO inches. In the deltas of the Ganges and Maha nadi, rain falls to the extent of GO to 75 inches, and along the westertr coast of the Peninsula of India, between the Syhadri mountains and the sea, also on the southern slopes ol the Himalaya, along the valley of the Brahmapittra, in Arztkan, and the delta of the Imwadi, the rainfall ranges from GO to over 200 inches.
The chief fall occurs between May and October while the S.W. monsoon is prevalent, except on the S.E. part of the Madras coast, where heavy rains fall from October to December while the N.E. monsoon blows, and showers occur from Christmas time to February in most parts of India. On thc Western Ghats and in the tract between them and the sea, the fall is from 70 to 100 inches, and as much as 250 inches on the west face of the mountains. Along the east coast of the Bay of Bengal, in the eastern districts of the Bengal Presidency, and along the foot and outerslopesof the Himalaya, it is100 inchesor more.
It may be said generally that India east of the 80th meridian ha.s a rainfall of more than 80 inches; but less than 30 inches falls in the Panjab, over a considerable part of the N.W. Provinces, over a large part of Rajputana and Kattyawar, and in almost all the Dekhan and Mysore.
In the southern portion of the Panjab, and in Sind and the most westerly part of Rajputana, the rainfall is less than 15 inches, and these are either actual desert, or agriculture is impossible without artificial irrigation.
The regions which suffer most from droughts and famines have average rainfalls between 20 and 35 inches, and in all of them seasons of scarcity or fatnine often recur. In these regions occurred the great famines of 1837-38 in the N.1V. Pro
vinces, of 1868-69 in Itajputana, and of 1876-77 over nearly the whole of the Peninsula of Southern India, and mainly due to failure of S.W. monsoon.
The eastern districts of Bengal and Assam, Burma, the strip between the Western Ghats and the sea, and the upper valley of the Nerbadda, have a rainfall sufficiently abundant to be exempt from all risk of drought, and Sind is protected by ttrtificial irrigation from the Indus. On the other hand, droughts are of frequent occurrence--(1) in the west and the south parts of the N.W. Pro vinces, and that part of the Panjab ea-st of the Sutlej ; (2) in the west and north parts of Raj putana, and the central plateau which borders on the N.W. Provinces; (3) the districts of. Bom bay above the Western Ghats, and the districts of Madras above the Eastern Ghats, together with the southern and western region of Hyderabad and all Mysore, except the strip lying close along the Western Mato ; (4) tho disttrielz of Madras along the east coast and at the extretultyof the Peninsula.
The rainfall in India proper fluctuate* as art 50 per cent. on either able of the average. In Madras!, the average during the GG years 1813 to 1879 was 48.51 indica, but In 1832 there fell 18.45 inches, and in 1827 the fall was 88-41 inches.
The rainfall at Bombay in the five months' Jima to October during the 50 years 1817 to IVA inclusive, ranged from 33.97 in 1821 to 121-98 inches in 1828.
In Calcutta the rainfall in the year averages 63 inches ; but in 1837 only 43-61 inchea fell, while in 1871 the quantity wax 93'31 inches.
Bangalore, Mysore, Tunikur, and Shemoga are towns in the Mysore territories all of which are in the region of scant rainfall, and any failure of the rains involves dearth, even famine. In 1876 and 1877 the rains thus failed in Mysore, and upwards of a million of its people perished.
There is a rainless region about the Red Sea, because the Red Sea for the most part lies within the north - east trade-wind region, and these winds, when they reach that region, are dry winds, for they have as yet in their course crossed no wide sheets of water from which they could take up a supply of vapour.
In 1876-77, a year of a great famine in the Pen insula, there was an unusual northerly tendency on the winds all down the Peninsula. Cycles of variation are known to occur in the spottiness of the sun's surface, certainly one, the duration of which is about 11 years ; and the inquiries of Mr. Meldrum have shown the probability that about the time when the sun is most spotted, the rainfall is about 15 per cent. greater than when it is least spotted. But inquirers have not been able to detect anything like a distinct cyclical variation amid the much greater variations that follow no such law.—Fanti2ze Commissioners' Rep.; Ofadras Observatory Records; Moral and Material Progress ; F. Blanford ; Tennent's Ceylon; Hooker; Thomson's Travels; Maury's Phys. Geog. ; .Records of Trig. Survey.