The strike of all the rocks (gneiss with granite veins) seemed to be north-east, and dip north-west 30 degrees. Such also were the strike and dip on another spur from Donkia, north of this, which I ascended to 19,000 feet, on the 26th of September: it abutted on the scarped precipices, 3000 feet high, of that mountain. I had been attracted to the spot by its bright orange-red colour, which I found to be caused by peroxide of iron. The highly crystalline nature of the rocks, at these great elevations, is due to the action of veins of fine-grained granite, which sometimes alter the gneiss to such an extent that it appears as if fused into a fine granite, with distinct crystals of quartz and felspar; the most quartzy layers are then roughly crystallized into prisms, or their particles are aggregated into spheres composed of concentric layers of radiating crystals, as is often seen in agates. The rearrangement of the mineral constituents by heat goes on here just as in trap, cavities filled with crystals being formed in rocks exposed to great heat and pressure. Where mica abounds, it becomes black and metallic; and the aluminous matter is crystallised in the form of garnets. Illustration--SUMMIT OF FORKED DONKIA, AND "GOA" ANTELOPES. At these great heights the weather was never fine for more than an hour at a time, and a driving sleet followed by thick snow drove me down on both these occasions. Another time I ascended a third spur from this great mountain, and was overtaken by a heavy gale and thunderstorm, the latter is a rare phenomenon: it blew down my tripod and instruments which I had thought securely Propped with stones, and the thermometers were broken, but fortunately not the barometer. On picking up the latter, which lay with its top down the hill, a large bubble of air appeared, which I passed up and down the tube, and then allowed to escape; when I heard a rattling of broken glass in the cistern. Having another barometer* [This barometer (one of Newman's portable instruments) I have now at Kew: it was compared with the Royal Society's standard before leaving England; and varied according to comparisons made with the Calcutta standard 0.012 during its travels; on leaving Calcutta its error was 0; and on arriving in England, by the standard of the Royal Society, +.004. I have given in the Appendix some remarks on the use of these barometers, which (though they have obvious defects), are less liable to derangement, far more portable, and stand much heavier shocks than those of any other construction with which I am familiar.] at my tent, I hastened to ascertain by comparison whether the instrument which had travelled with me from England, and taken so many thousand observations, was seriously damaged: to my delight an error of 0.020 was all I could detect at Momay and all other lower stations. On my return to Dorjiling in December, I took it to pieces, and found the lower part