They now turned back in search of Mr. Merton; and as they ascended the hill, Agnes began asking her mother some questions about light-houses. “They are buildings,” said Mrs. Merton, “erected on rocks near the sea-shore, in which lights are exhibited all night, for the direction of mariners.” “They are sometimes called pharos, are they not?” asked Agnes. “That name,” said Mrs. Merton, “was given to them from the first light-house of which we have any record having been erected on the island of Pharos, near Alexandria, about two hundred and eighty years before Christ. The principal light-houses in Britain, however, are that on the Bell rock, opposite the Firth of Tay, and that on the Eddystone rocks, opposite to Plymouth Sound.” “Why are light-houses made so high?” asked Agnes. “In order that the light may be seen at a greater distance,” replied her mother; “and for the same reason the light is always placed in the upper part of the building.” “Of what does the light consist?” “It is an Argand lamp,” replied Mrs. Merton, “with a reflector behind it, made of silver strengthened with copper and highly polished.” “I wonder,” said Agnes, “how the sailors know when it is a light-house. I should think that when they are at sea, they must be in danger of mistaking it for the light of a common house.” “Yes,” said Mrs. Merton, “that has been done; and to prevent the possibility of such a mistake occurring again, as it would be a very serious one, contrivances have been devised for making the lights turn round, or of placing two in the light-house of different colours, so that the light of the light-house can never be mistaken for any other.” “I suppose that on the Bell rock is one of those that turn round,” said Agnes, “for I remember when I was in Edinburgh and down at Leith, seeing it appear, disappear, and then appear again, till I was tired of looking at it.” They now reached the light-house where they found Mr. Merton, who had been amused during their absence, hearing the history of the old couple who formerly lived there, and who, for nineteen years, had never, either of them, had a single hour’s illness. They now resumed their seats in the carriage, and returned in the way they came, till they were within a short distance of Freshwater, when they turned to the left, to take the road to Black Gang Chine. The road was extremely uninteresting, consisting of a series of narrow lanes between high hedges like those of Devonshire; but without the beautiful views, which in that county delight the eye, whenever a field-gate makes a break in the hedge. “What a dull country!” cried Agnes. “It is a very fertile one, however,” said her father, “as it has been found, on calculation, that the Isle of Wight produces seven times as much corn and other articles of human food as would suffice for the wants of its inhabitants.”