PROBABLY in no country in the world is the necessity for the due adjustment of those natural influences which produce fertility and salubrity of climate more fully exemplified than in India. For instance, the cooling influence of the Himalayan Mountain range is essential to produce rain, from the warm and moist exhalations of the Bay of Bengal. But, owing to the occasional irregularities of the season, causing sometimes an excess, and at other times a deficiency of moisture, the skill of the Engineer is required to reduce these irregularities to a minimum. The Author has been engaged during the greater part of a quarter of a century on some of the most important irrigation works in Northern India, and an account of the most prominent features of the system may possibly be of interest.Twenty-five years ago canals were supposed to be injurious to the climate, and Kurnaul was cited as an example of a military station having to be deserted owing to the unhealthiness caused by the Western Jumna Canal. Further experience has, howe,ver, shown, that defective drainage was the cause of the evil, for the swamps would have existed even had there been no canal. Hence it appears that the proper remedy is to drain these swamps, not into the river, but into the desert, for when the Jumna is in flood, it is on a higher level than the marshes. In this particular, not only should the swamps be drained, but more of the inundation water should in the first instance be turned into them, so as to warp them up, allowing this water after it had parted with most of its silt to flow into the desert. A few hhousand cubic feet per sec,ond disposed of in this way, during the season when the Jumna is in flood, from April to September, would go far to improve the clinlate in that neighbourhood, while the land watered would be fertilized as in Egypt.An opinion now prevails, that irrigation, under a proper system, has a tendency to improve rather than to injure the climate ; and accordingly the water has of late years been carried through military stations, instead of so as to avoid them.