What deep root their preaching took in these parts is still evident. Still the weary fight between the two religions continues.

The first traveller of note through this distracted Europe was a Frenchman named Arculf, a Christian bishop. When he had visited the Holy Land and Egypt his ship was caught in a violent storm and driven on to the west coast of Scotland. After many adventures Arculf found himself at the famous convent of Iona, made welcome by an Irish monk Adamnan, who was deeply interested in Arculf's account of his wanderings, and wrote them down at his dictation, first on waxed tablets, copied later on to parchment. How tenderly the two monks dwell on all the glories of Jerusalem. "But in that beautiful place where once the Temple had been, the Saracens now frequent a four-sided house of prayer, which they have built, rudely constructing it by raising boards and great beams on some remains of ruins, which house can hold three thousand men at once." And Arculf draws on the waxed tablet the picture of some church or tomb to make his narrative clearer to his friend Adamnan.

Perhaps the most interesting part of all the travels is the account of the lofty column that Arculf describes in the midst of Jerusalem.

"This column," he says, "as it stands in the centre of the heaven, shining straight down from above, proves that the city of Jerusalem is situated in the middle of the earth."

Arculf's journey aroused great interest among the newly converted Christians of the north, and Willibald, a high-born Englishman, started off in 721 to explore farther. But the road through Europe was now full of danger. The followers of Mohammed were strong, and it required true courage to face the perils of the long journey. Willibald was undaunted, and with his father and two brothers he sailed from Southampton, crossed to France, sailed up the Seine to Rouen, and reached Italy. Here the old father died. Willibald and his brothers travelled on through "the vast lands of Italy, through the depths of the valleys, over the steep brows of the mountains, over the levels of the plains, climbing on foot the difficult passes of the Alps, over the icebound and snow-capped summits," till they arrived at Rome. Thence they made their way to Syria, where they were at once thrown in prison by Mohammedan conquerors. They were brought before the ruler of the Mohammedan world, or Khalif, whose seat was at Damascus. He asked whence they came.

"These men come from the western shore, where the sun sets: and we know not of any land beyond them, but water only," was the answer.

Such was Britain to the Mohammedans. They never got a footing in that country: their Empire lay to the east, and their capital was even now shifting to Bagdad.

But before turning to their geographical discoveries we must see how Cosmas, the Egyptian merchant-monk, set the clock back by his quaint theories of the world in the sixth century. Cosmas hailed from "Alexander's great city." His calling carried him into seas and countries remote from home. He knew the Mediterranean Sea, the Persian Gulf, and the Red Sea. He had narrowly escaped shipwreck in the Indian Ocean, which in those days was regarded with terror on account of its violent currents and dense fogs. As the ship carrying the merchant approached this dread region, a storm gathered overhead, and flocks of albatross, like birds of ill-omen, hovered about the masts.

"We were all in alarm," relates Cosmas, "for all the men of experience on board, whether passengers or sailors, began to say that we were near the ocean and called out to the pilot: 'Steer the ship to port and make for the gulf, or we shall be swept along by the currents and carried into the ocean and lost.' For the ocean rushing into the gulf was swelling with billows of portentous size, while the currents from the gulf were driving the ship into the ocean, and the outlook was altogether so dismal that we were kept in a state of great alarm."

That he eventually reached India is clear, for he relates strange things concerning Ceylon. "There is a large oceanic island lying in the Indian Sea," he tells us. "It has a length of nine hundred miles and it is of the like extent in breadth. There are two kings in the island, and they are at feud the one with the other. The island, being as it is in a central position, is much frequented by ships from all parts of India, and from Persia and Ethiopia, and from the remotest countries, it receives silk, aloes, cloves, and other products . . . farther away is the clove country, then Tzinista (China), which produces silk. Beyond this there is no other country, for the ocean surrounds it on the east."

Cosmas was the first to realise that China was bounded on the east by the ocean. He tells us a good story about the "Lord of India," who always went to war with two thousand elephants. "Once upon a time this king would lay siege to an island city of the Indians, which was on every side protected by water. A long while he sat down before it, until, what with his elephants, his horses, and his soldiers, all the water had been drunk up. He then crossed over to the city dryshod and took it."

But, strange as are the travels and information of Cosmas, still stranger is his Christian Topography. His commercial travelling done he retired, became a devout Christian monk, and devoted his leisure time in trying to reconcile all the progress of geographical knowledge with old Biblical ideas.

He assures us that the world is flat and not round, and that it is surrounded by an immense wall supporting the firmament. Indeed, if we compare the maps of Cosmas in the sixth century with those of the Babylonians thousands of years before, there is mighty little difference. With amazing courage he refutes all the old theories and draws the most astounding maps, which, nevertheless, are the oldest Christian maps which survive.