Delaware Medicine Man.

For several days, Capt. Wolff, the chief of our Delawares, had been ailing, this morning I noticed some unusual preparations in their camp, on inquiring I was told that, in the woods, Capt. Wolff, who was very sick, was undergoing the Indian ceremony of "incantation," by one of the tribe, who was "a great medicine man." The ceremony was conducted in secret, but I found out afterwards the place, and from the mode which was explained to me, I understood the rite perfectly. A small lodge, composed of the branches of trees, high enough for a man to sit upright in, was built; in this the patient was placed in a state of perfect nudity. "The Medicine Man," who is outside, takes a "pipe," filled with "kinnikinick and tobacco," and hands it in to the patient. While the Medicine Man recites the "all powerful words," the patient puffs away until the lodge is filled with smoke; when the poor devil is almost suffocated, and exhausted, he is taken out, wrapped in his blankets, and conveyed to his own lodge.

Feeling anxious about him, I went in to see him about an hour afterwards; I found him in a high state of febrile excitement, which had, no doubt, been increased by his extraordinary treatment; he complained of dreadful headache and pain in his back. He thought he was going to die. I told him if he would submit to my advice I thought I could cure him—he consented, and I administered ten grains of calomel, and four hours afterwards half oz. of Epsom salts. He is now considerably relieved; and I think by the morning he will be well. Indigestion was the cause of his suffering. I made him some of the arrowroot, which thanks to your usual foresight I found stowed away in my trunk. I shall reserve it for similar occasions.

Col. Fremont has not yet arrived.

Our quarter master has suddenly discovered that his commissariat is empty, and talks of sending to Fort Riley for fresh supplies to-morrow; if he does I will forward a package of letters to you, which please preserve from public eye.

Two Delawares and a muleteer are now preparing to go to "Fort Riley" for supplies. Capt. Wolff is better; by evening I hope he will be perfectly well. I think if I had not treated him he would have probably died. Another "incantation" would certainly have killed him. I shall continue to write to you. Most probably we shall be detained here a week longer; it is now the 20th October, and I am afraid Col. Fremont is seriously ill; you will, of course, have heard of his return, and I shall look forward to receive by him happy tidings from all those I love.

Professor Espy's Theory of Rain

I have had occasion to observe that the immense clouds of smoke which filled the atmosphere continually during the time the prairies were on fire, were condensed during the cold of the night, sometimes forming rain, but always heavy dew, which I did not observe before the prairies were burning.

I think Prof. Espy says that artificial rain can be produced by smoke from large fires, and from the observations I have made I coincide in that theory.

It is not unlikely that the Indians, who have from the earliest knowledge of the prairie country annually set the high rank grass on fire, did it to afford artificial moisture for the immense tracts of buffalo grass plains, an which subsist hundreds of thousands of buffalo, elk, and deer. No rain falls at certain seasons, and without dew the grass would be all burnt up by the scorching heat of the sun.

The Indians, I believe, practically put into operation the theory of Espy—knowing from experience that smoke is condensed into dew.

On the Kansas River the dew fell very heavily. I found it necessary while doing guard to cover myself with my India-rubber poncho, to prevent my clothes from becoming saturated with water.

Last night our camp was visited with a heavy storm of rain and sleet; it was bitter cold. It rained considerably yesterday, but the temperature was not lower than 65º. The wind increased during the night, and one sudden gust blew our cotton tent completely over, exposing us to the peltings of the merciless storm of sleet. Several of us essayed to raise the tent, but the ground had become saturated with moisture, and afforded no hold for our tent-pins, and we consequently lay down, wrapped ourselves in our India-rubber blankets, and bewailed our fate.

We presented an interesting picture when the daylight came. Many of our clothes, which were lying loosely in the tent, were blown some distance from camp, and we were all drenched to the skin. The weather cleared off at sunrise and around a large camp-fire we dried our clothes and passed jokes on each other ' s distressing appearance. Winter seems to have suddenly set in; the thermometer indicated, at sunrise, 34º ("por peccados," as the Spaniards say.) Many of our animals pulled up their picket-pins, and sought shelter in the woods. My pony is missing, among others, and on myself and on no one else devolves the delightful duty of finding him. I have put on, for the first time, my waterproof boots, as I have a wet road, and, probably, a long distance to walk , before I find my horse. He is safe enough on the creek; the Indians saw him while hunting up theirs.