25th.--The morning was cold and bright, and as the sun rose the day became beautiful. A party of twelve Indians came down from the mountains to trade pine nuts, of which each one carried a little bag. These seemed now to be the staple of the country; and whenever we met an Indian, his friendly salutation consisted in offering a few nuts to eat and to trade; their only arms were bows and flint-pointed arrows. It appeared that in almost all the valleys the neighboring bands were at war with each other; and we had some difficulty in prevailing on our guides to accompany us on this day's journey, being at war with the people on the other side of a large snowy mountain which lay before us.

The general level of the country appeared to be getting higher, and we were gradually entering the heart of the mountains. Accompanied by all the Indians, we ascended a long ridge, and reached a pure spring at the edge of the timber, where the Indians had waylaid and killed an antelope, and where the greater part of them left us. Our pacific conduct had quieted their alarms; and though at war among each other, yet all confided in us-- thanks to the combined effects of power and kindness--for our arms inspired respect, and our little presents and good treatment conciliated their confidence. Here we suddenly entered snow six inches deep, and the ground was a little rocky, with volcanic fragments, the mountain appearing to be composed of such rock. The timber consists principally of nut pines, (pinus monophyllus,) which here are of larger size--12 to 15 inches in diameter; heaps of cones lying on the ground, where the Indians have gathered the seeds.

The snow deepened gradually as we advanced. Our guides wore out their moccasins; and putting one of them on a horse, we enjoyed the unusual sight of an Indian who could not ride. He could not even guide the animal, and appeared to have no knowledge of horses. The snow was three or four feet deep on the summit of the, pass; and from this point the guide pointed out our future road, declining to go any further. Below us was a little valley; and beyond this the mountains rose higher still, one ridge above another, presenting a rude and rocky outline. We descended rapidly to the valley: the snow impeded us but little; yet it was dark when we reached the foot of the mountain.

The day had been so warm that our moccasins were wet with melting snow; but here, as soon as the sun begins to decline, the air gets suddenly cold, and we had great difficulty to keep our feet from freezing--our moccasins being frozen perfectly stiff. After a hard day's march of 27 miles, we reached the river some time after dark, and found the snow about a foot deep on the bottom--the river being entirely frozen over. We found a comfortable camp, where there were dry willows abundant, and we soon had blazing fires. A little brandy, which I husbanded with great care, remained, and I do not know any medicine more salutary, or any drink (except coffee) more agreeable, than this in a cold night and after a hard day's march. Mr. Preuss questioned whether the famed nectar ever possessed so exquisite a flavor. All felt it to be a reviving cordial.

The next morning, when the sun had not yet risen over the mountains, the thermometer was at 2° below zero; but the sky was bright and pure, and the weather changed rapidly into a pleasant day of summer. I remained encamped in order to examine the country, and allow the animals a day of rest, the grass being good and abundant under the snow.

The river is fifty or eighty feet wide, with a lively current, and very clear water. It forked a little above our camp, one of its branches coming directly from the south. At its head appeared to be a handsome pass; and from the neighboring heights we could see, beyond, a comparatively low and open country, which was supposed to form the valley of the Buenaventura. The other branch issued from a nearer pass, in a direction S. 75° W., forking at the foot of the mountain, and receiving a part of its waters from a little lake. I was in advance of the camp when our last guides had left us; but, so far as could be understood, this was the pass which they had indicated, and, in company with Carson, to-day I set out to explore it. Entering the range, we continued in a northwesterly direction up the valley, which here bent to the right. It was a pretty open bottom, locked between lofty mountains, which supplied frequent streams as we advanced. On the lower part they were covered with nut-pine trees, and above with masses of pine, which we easily recognised, from the darker color of the foliage. From the fresh trails which occurred frequently during the morning, deer appeared to be remarkably numerous in the mountain.

We had now entirely left the desert country, and were on the verge of a region which, extending westward to the shores of the Pacific, abounds in large game, and is covered with a singular luxuriance of vegetable life.

The little stream grew rapidly smaller, and in about twelve miles we had reached its head, the last water coming immediately out of the mountain on the right; and this spot was selected for our next encampment. The grass showed well in sunny places; but in colder situations the snow was deep, and began to occur in banks, through which the horses found some difficulty in breaking a way.

To the left, the open valley continued in a southwesterly direction, with a scarcely perceptible ascent, forming a beautiful pass, the exploration of which we deferred until the next day, and returned to the camp.

To-day an Indian passed through the valley, on his way into the mountains, where he showed us was his lodge. We comprehended nothing of his language; and, though he appeared to have no fear, passing along in full view of the camp, he was indisposed to hold any communication with us, but showed the way he was going, and pointed for us to go on our road.