In the Eastern Seas

by William Henry Giles Kingston

At length Mr Hooker, having unpacked his books, various instruments, and other articles, begged that the cases might be stowed away below. His directions were promptly obeyed, and having surveyed his cabin, he seemed satisfied that all was in perfect order.

“Now, young gentleman,” he said, with a pleasant smile which won my confidence, “I daresay you would like to know what all these things are for. Some are for taking the latitude and longitude, ascertaining the exact position of places on the earth’s surface. Others are for measuring the height of mountains, some the temperature of the air and water, and so on. Then I have cases for creatures which move in the water or fly in the air, which walk or crawl on the earth or burrow beneath it; and I have the means of shooting them or trapping them. Those I can, I hope to preserve alive; and if not, to be able to exhibit to my scientific friends, when I return home, the forms of some perfect, the skins of others, and the skeletons of others. And now, having told you thus much, I must leave you to guess what I profess myself to be. One thing I can tell you, I know very, very little compared to what there is to be known. I hope to gain more knowledge but I am very well aware that, gain all I can, I can but add a very small portion to what is already known, and a still smaller compared to what is to be ascertained. Here comes the captain. We are old friends, and that induced me to select this ship for my voyage. Are you his son?”

“No, sir,” I answered; “but he is a very kind friend of mine; and were it not for him, I know not what would have become of me and my sister.”

The Bussorah Merchant had a fine passage down Channel, and taking her departure from the Land’s End, stood across the Bay of Biscay. Four days afterwards the captain told us that we were in the latitude of Cape Finisterre, but no land was to be seen. Another eight days, with the wind abeam, carried us into the neighbourhood of the island of Madeira.

“Would not it be as well to have a look at it, sir,” I said, “and then we shall better know where we are.”

The captain smiled. “That is not at all necessary,” he answered. “By the observations we are able to take with the perfect instruments we possess, we are able at all times to ascertain our exact position on the ocean; and we might thus sail round either Cape Horn or the Cape of Good Hope to New South Wales without once sighting land till we were about to enter Port Jackson.”

“It is very wonderful,” I said. “What puzzles me is how you can find the longitude. I know you get the latitude by seeing how high the sun is above the horizon at noon, and then with the aid of the nautical almanac you can easily work out the calculation.”

“With the aid of the chronometer we can as easily ascertain the longitude, though the calculation is a little longer,” answered Captain Davenport. “I can explain it to you more easily. The chronometer shows us the exact time at Greenwich. We know by our nautical almanac that, at a certain hour on a certain day, the sun will have attained at Greenwich a certain altitude. When on that day and that hour we find that the sun is so many minutes behind hand in attaining that altitude, we know we must be a certain distance further to the west, as, the world turning from west to east, the more westerly a place is the longer it will be before the sun appears there. If, on the contrary, we find the sun has gained a fixed altitude some time before it would have gained that altitude at Greenwich, we know that we must be to the east of Greenwich, or have met the sun sooner than the people at Greenwich have done. Thus, the further we sail east day after day, the sooner we see the sun; while the further we sail west, the longer the time which passes before he shines upon us.”

“I think I have an idea about it now, sir,” I exclaimed; “and I should be very much obliged if you will show me how to take an observation and to make use of the books, as well as to work out the calculations. Why, may I ask, do you cry Stop, sir, to the second officer or to Mr Thudicumb, who are watching the chronometer while you are taking an observation?”

“That they may mark the exact moment shown on the chronometer, while I mark the sun’s elevation as shown on the index of the sextant.”