7th.--At sunrise this morning a very interesting scene took place in the arrival of the great annual Harar caravan,--a large body, composed of an aggregate of numerous small caravans, which all march together that their combined strength may give mutual support. Down the whole breadth of the plain, like a busy stream of ants, they came in single file, one camel's nose tied to his leader's tail. Immediately on their flanks were Somali, armed with spear and bow, the men who tended them and looked after the loading. Outside them again were occasional detachments of men riding ponies, all armed, and guarding the caravan from sudden surprise or attack. In this caravan alone there were about three thousand people, as many head of cattle, and 500 or more slaves, all driven chained together for sale in the market. A little later the same morning a second excitement enlivened our little camp in the approach of a man-of-war, which came sailing up the coast in full sail, looking like a giant swan in contrast to the little ducks of native shipping. It was the Hon. East India Company's schooner Mahi, commanded by Lieutenant King, conveying our Captain, Lieutenant Burton, and the complement of the expedition. Arrived in the harbour, we saluted them with our small-arms, and went on board to pay respects and exchange congratulations. King then gave us a hospitable entertainment, and we all repaired on shore. The same evening a thundering salute from the Mahi was fired, to assure the Somali we were travelling under the auspices of the British Government, and King departed with his vessel. Lieutenant Burton now took occupation of the centre tent with Herne, and the party was complete. We were then severally appointed to our respective duties, Lieutenant Burton commanding; Stroyan chief surveyor; Herne, photographer, geologist, and assistant-surveyor; whilst I was to be a Jack-of-all-trades, assisting everybody, looking after the interests of the men, portioning out their rations, setting the guards, and collecting specimens of natural history in all its branches. The central tent was fixed as a place of rendezvous for all to flock to in case of any sudden alarm. Here I appended my guns and sword, whilst my revolver-pistol and dirk were placed within my belt by day, or under my pillow by night. I made the whole guard sleep with their arms in rear of the camp, where it was most likely any attack might be expected. As so many men were necessarily brought on duty by watching the cattle grazing in the day-time, I only posted two sentries by night to watch the camp--one with the guard in the rear, the other over the cattle in front; whilst we Englishmen and the Balyuz occasionally patrolled the camp to see that the sentries were on the alert.