Mr. J.J. Mcgillivray, who has been for many years in the United States mineral survey service, has some interesting things to say about the overflow of the Colorado desert, which has excited so much comment, and about which so many different stories have been told:

"None of the papers, so far as I know," said Mr. McGillivray, "have described with much accuracy or detail the interesting thing which has happened in the Colorado desert or have stated how it happened. The Colorado desert lies a short distance northwest of the upper end of the Gulf of California, and contains not far from 2,500 square miles. The Colorado River, which has now flooded it, has been flowing along to the east of it, emptying into the Gulf of California. The surface of the desert is almost all level and low, some of it below the sea level. Some few hundreds of years ago it was a bay making in from the Gulf of California, and then served as the outlet of the Colorado River. But the river carried a good deal of sediment, and in time made a bar, which slowly and surely shut off the sea on the south, leaving only a narrow channel for the escape of the river, which cut its way out, probably at some time when it was not carrying much sediment. Then the current became more rapid and cut its way back into the land, and, in doing this, did not necessarily choose the lowest place, but rather the place where the formation of the land was soft and easily cut away by the action of the water.

"While the river was cutting its way back it was, of course, carrying more or less sediment, and this was left along the banks, building them all the time higher, and confining the river more securely in its bounds. That is the Colorado River as we have known it ever since its discovery. Meantime, the water left in the shallow lake, cut off from the flow of the river, gradually evaporated - a thing that would take but a few years in that country, where the heat is intense and the humidity very low. That left somewhere about 2,000 miles of desert land, covered with a deposit of salt from the sea water which had evaporated, and most of it below the level of the sea. That is the Colorado desert as it has been known since its discovery.

"Then, last spring, came the overflow which has brought about the present state of affairs. The river was high and carrying an enormous amount of sediment in proportion to the quantity of water. This gradually filled up the bed of the stream and caused it to overflow its banks, breaking through into the dry lake where it had formerly flowed. The fact that the water is salt, which excited much comment at the time the overflow was first discovered, is, of course, due to the fact that the salt in the sea water which evaporated hundreds of years ago has remained there all the time, and is now once more in solution.

"The desert will, no doubt, continue to be a lake and the outlet of the river unless the breaks in the banks of the river are dammed by artificial means, which seems hardly possible, as the river has been flowing through the break in the stream 200 feet wide, four feet deep, and flowing at a velocity of five feet a second.

"It is an interesting fact to note that the military survey made in 1853 went over this ground and predicted the very thing which has now happened. The flooding of the desert will be a good thing for the surrounding country, for it does away with a large tract of absolutely useless land, so barren that it is impossible to raise there what the man in Texas said they mostly raised in his town, and it will increase the humidity of the surrounding territory. Nature has done with this piece of waste land what it has often been proposed to do by private enterprise or by public appropriation. Congress has often been asked to make an appropriation for that purpose."

Mr. McGillivray had also some interesting things to say about Death Valley, which he surveyed.

"It has been called a terra incognita and a place where no human being could live. Well, it is bad enough, but perhaps not quite so bad as that. The great trouble is the scarcity of water and the intense heat. But many prospecting parties go there looking for veins of ore and to take out borax. The richest borax mines in the world are found there. The valley is about 75 miles long by 10 miles wide. The lowest point is near the center, where it is about 150 ft. below the level of the sea. Just 15 miles west of this central point is Telescope peak, 11,000 ft. above the sea, and 15 miles east is Mt. Le Count, in the Funeral mountains, 8,000 ft. high. The valley runs almost due north and south, which is one reason for the extreme heat. The only stream of water in or near the valley flows into its upper end and forms a marsh in the bed of the valley. This marsh gives out a horrible odor of sulphureted hydrogen, the gas which makes a rotten egg so offensive. Where the water of this stream comes from is not very definitely known, but in my opinion it comes from Owen's lake, beyond the Telescope mountains to the west, flowing down into the valley by some subterranean passage.

The same impurities found in the stream are also found in the lake, where the water is so saturated with salt, boracic acid, etc., that one can no more sink in it than in the water of the Great Salt lake; and I found it so saturated that after swimming in it a little while the skin all over my body was gnawed and made very sore by the acids. Another reason why I think the water of the stream enters the valley by some fixed subterranean source is the fact that, no matter what the season, the flow from the springs that feed the marsh is always exactly the same.

"The heat there is intense. A man cannot go an hour without water without becoming insane. While we were surveying there, we had the same wooden cased thermometer that is used by the signal service. It was hung in the shade on the side of our shed, with the only stream in the country flowing directly under it, and it repeatedly registered 130°; and for 48 hours in 1883, when I was surveying there, the thermometer never once went below 104°." - Boston Herald.