For the first three days all went smoothly, the speed of the whole being regulated by the pace of the slowest vessel in the squadron. On the evening of the third day, however, the weather showed signs of changing. They had been sailing along with a good following breeze, the sky overhead a deep, cloudless, sapphire blue, and the sea smooth enough to relieve them from all uneasiness. Now, however, the sun was sinking toward the horizon like a ball of dull red copper, and the western sky, instead of being clear as previously, was heavy with black clouds that were banking up and threatening to obscure the sun ere it set. Overhead, too, deep violet clouds made their appearance, tinged here and there to lurid red and orange by the rays of the fast-disappearing luminary. The air, moreover, felt dull and heavy, and carried a peculiar odour not unlike brimstone. This singular condition of the atmosphere was not without its effect on the men, who felt listless and disinclined to work. A sense of impending peril seemed to be hanging over all. The wind, too, was gradually dying away, and came fitfully and at intervals in hot, sulphurous puffs. The sea, which had been sparkling in thousands of tiny wavelets in the rays of the sun, began to assume a dark and oily appearance; and a long swell was beginning to make itself felt, causing the sails, as they drooped against the masts, to flap noisily with a sound like the crack of an arquebuse. Gradually the sky grew blacker and more overcast, and the sea assumed the appearance of ink. The five ships of the squadron were all well within sight of one another, and lay motionless save for their uneasy heaving to the swell which was now fast-rising. Having lost steerage-way, they were "boxing the compass", that is, were heading first in one direction and then in another, their bows slowly swinging until they pointed in various directions. Cavendish was on deck, looking anxiously at the sky, and presently he gave the order to all hands to shorten sail, and hailed the ship lying nearest to him to do the same. The other vessels were lying too far away for a hail to carry, and there was no wind to lift the signal flags if hoisted; but the commodore was relieved to see the remainder of the fleet follow his example. In a few moments the canvas of the whole squadron was seen coming heavily down or being rolled up on the yards; and before very long all the ships were either under bare poles or being snugged down with everything secured ready for any emergency.