Mr. Gregory's Lecture.

Mr. Charles A. Gregory, of Chicago. delivered last evening, under the auspices of the Harvard Natural History society, an extremely interesting lecture on "The Great American Desert," or, as Mr. Gregory calls it, "The Arid Region."

The lecturer spoke as follows: Roughly speaking, the arid region extends from the 100th meridian to the Pacific ocean, between the 100th and the 105th lies the so called "debatable ground." an enormous piece of territory upon which agriculture is in some years profitable, in others, not. Washington Oregon, and the northern part of California are excluded from this rough outline. The total area is about 1.300,000 square miles, or 40 per cent. of the United States. The question is how to make this region profitable for agriculture.

The flora of the arid region consists of good timber in the north and in the south at great heights; brush wood in the north, cactus and similar plants in the south. The grass in the western part is excellent for grazing purposes. The rainfall in this region is from 10 to 15 inches per year, while 23 inches are necessary for profitable agriculture. The snow in the mountains, however, fills the streams and brooks, and although a great deal of the water is wasted, a large amount of it is used to great advantage by irrigation. Reservoirs are being built in case these streams dry up, and thus millions and millions of acres are being reclaimed.

In southern California and along the Rio Grande irrigation is carried on very scientifically and advantageously. The method used at present is to tap a stream up in the mountains; water is led off by long canals down into the valleys, and each farmer in turn taps the canal to irrigate his land. The laterals are at times but 100 feet apart, and the water flowing through them moistens all the intervening ground.

The results or irrigation are surprising, as can be proved by the immense amount invested in these canals. There are more than 12000 miles of canals, with 300,000 miles of laterals, an investment of over $100,000,000. Alfalfa is cultivated to a great extent on ranches, and where formerly forty acres of grazing ground were needed for one head of stock, now one acre of alfalfa supplies food for two and a half heads.

Mr. Gregory recently visited the arid lones west of the Papas river. At present work is being rapidly pursued in the construction of a very large canal, and it is expected that this part of the arid region will soon be a most fertile land. A large number of the the smaller rivers cross this territory. The frost is never severe; the mean temperature is 620, and the summers are long and hot. The soil of the arid region is rich, and the opportunities for irrigation are great. The population of the United States is rapidly increasing, and the rising generation will see it reach 200,000,000. The arid region alone, if properly cultivated, could supply them all with the necessaries of life.