1887.] H. F. Blanford — Infiuence of Indian Forests on the Bainfall. 13 



and the Jhelum (two of the five rivers of the Punjab), and about 50 miles 

 to the south of Lahore, a vigorous forest has been established, by 

 planting and irrigating the planted land from the Bari doab canal. 

 The forest area covers 31 f square miles and has now been established 

 16 years.* Outside the forest and to the east and south-east are lands 

 which are cultivated, also with irrigation from the canal ; and on the 

 margin of this tract, four miles from the forest, is the small civil station 

 of Chunian. Since 1864, a rainfall register has been kept regularly 

 at Vahn (within the forest, half a mile distant from the nearest forest 

 boundary) , and also at Chunian ; and since 1870, a third register has 

 been kept at Bhambeh, a station on the Bari doab canal, in a position 

 very similar to Chunian, but 13 miles to the north-east of the forest 

 boundary and 19 miles north-east from Ghanga Manga or Yahn. 



The rainfall chart of the Punjab shews that, in this part of the 

 province, there is a steady increase of rainfall in a north-east direction 

 or from Chunian to Bhambeh ; steady, that is to say, apart from the 

 influence of purely local conditions, and therefore, were the whole 

 surface of the tract such as it is immediately around Chunian and 

 Bhambeh, it might be anticipated that the mean rainfall of any inter- 

 mediate station should be intermediate between those of Chunian 

 and Bhambeh, in inverse proportion to their respective distances. The 

 mean rainfall of Bhambeh, deduced from 17 years' registers, is 17*27 

 inches ; that of Chunian, deduced from the same period, is 14*05 

 ins. If, then, Vahn, which is 19 miles from the former and 6|- 

 miles from the latter station, had a rainfall intermediate between the 



Works and now Secretary to the Government of India. " Two gauges are placed 

 side by side, the receivers are 4^ feet above tlie ground. One is an ordinary 

 tube gauge, measurements made witb a graduated rod. The other a Watsen's 

 continuous self-registering gauge, which is taken to pieces, cleaned and re-adjusted 

 on the 1st April yearly. The bearings of the gauge are silver plated copper tubes 

 and with very ordinary care in adjustment, they register very correctly. Instruc- 

 tions about registering rainfall are very distinct and I believe they are obeyed." 



* Mr. H. C. Hill, Conservator of Forests in the Punjab, writes, " Changa 

 Manga is a compact block of 20,242 acres, of which 8,399 are wooded with planted 

 Sissoo {Dalbugia Sissoo). The remainder is under ordinary scrub. The age of the 

 plantation dates back to 1866-67, but little was done for 3 years and the age of the 

 forest may be taken as 16 years. The trees (excepting those in the canal avenue 

 averaging 63 feet) of our best compartments average 50, 51 and 53 feet in height 

 and all compartments have an average of 40 or more." 



" The watering of the forest begins in April and goes on more or less till 

 September. Yery little of it ever gets a second watering in the year, but that 

 given is a good soaker of 3 or 4 feet depth of water. The ground to the east and 

 south except where 2 rahhs are touched, is all under cultivation and irrigated. 

 Irrigation mostly from June to April, 



