been met with at the Azores, and from the South Pole they have come even to the Cape of Good Hope.

Q. What causes a current from the poles to the equator?

A. In consequence of the great heat of the torrid zone, large portions of the waters of the ocean in that zone are taken up into the air in the form of vapour. In order to supply the place of the water so taken up, water proceeds from the direction of the poles towards the equator. By this means currents are formed from the poles to the equator.

Q. How does the rotation of the earth on its axis affect the currents of the ocean?

A. The waters of the ocean, as they proceed from the poles to the equator, pass from regions where the rotatory motion of the earth's surface is very slight, to those where it is exceedingly rapid; they cannot immediately acquire the rapid motion with which the solid parts of the earth revolve in the tropical regions, and they are accordingly left

rather behind. In other words, the ocean in tropical regions has a general movement from east to west, and the effect is very much assisted by the constant blowing of the trade-winds.

Q. What is the Gulf Stream?

A. It has been described as "an immense river of hot waters in the ocean." It issues from the Gulf of Mexico, and after sweeping along the eastern coast of North America, it skirts the Bank of Newfoundland, and then bends to the east across the Atlantic, as far as the Azores. Q. What course does the Gulf Stream take at the Azores ?

A. A portion of it turns towards the Straits of Gibraltar, the island of Madeira, and the Canaries, while another portion runs to the north-east, towards the coasts of Europe.

Q. What circumstances are said to have strengthened Columbus in his conjecture of the existence of a western continent?

A. Towards the close of the fifteenth century, before Europeans were ac

quainted with the existence of America, two bodies belonging to an unknown race of men were cast by the Gulf Stream on the coast of the Azores, and pieces of bamboo were brought by the same current to the shores of the small island of Porto Santo, near to Madeira.

Q. What further evidence have we of the Gulf Stream?

A. The fruit of trees which belong to the American torrid zone is every year deposited on the western coasts of Ireland and Norway; and on the shores of the Hebrides are collected the seeds of several plants, the growth of Jamaica, Cuba, and the neighbouring continent.

Q. At what rate of speed does the Gulf Stream move?

A. The rapidity of the current of the Gulf Stream varies in different parts. Its velocity is greatest when it issues from the Gulf of Mexico, and it then moves at the rate of about four miles an hour; but it proceeds across the Atlantic Ocean at about the rate of one mile and a half an hour.

Q. By what is the Gulf Stream principally distinguished?

A. By the high temperature and saltness of its waters, their indigo blue colour and the quantity of seaweed floating on its surface, and also by the heat of the surrounding atmosphere.

Q. What effect does the Gulf Stream produce on the climate of western Europe?

A. As the waters of that stream flow from the tropical regions, they bring warmth as well as moisture to the western portion of Europe.

Q. How may the directions of currents be ascertained?

A. By throwing bottles overboard with a piece of paper in them containing the date when the bottle was thrown into the sea, and the latitude and longitude of the spot at which that was done. If the bottle be picked up afterwards, the current may be found out.

Q. What is rain?

A. It is the vapour in the air condensed into water.

Q. From whence is the vapour which the air contains obtained?

A. It is obtained by means of evaporation; that is, by the air drawing off moisture in the form of vapour from the surface of the earth.

Q. By what means is the vapour contained in the atmosphere condensed, or turned into water?

A. By means of cold.

Q. How does cold convert the vapour in the air into water?

A. Cold diminishes the capacity of the air to hold vapour, for it is found that warm air is capable of holding in the state of vapour more water than cold air.

Q. What is dew?

A. It is the vapour or moisture contained in the atmosphere condensed, or turned into water, by coming into contact with bodies colder than the atmosphere. Dew, therefore, is the effect, not the cause, of the coolness contracted by bodies on exposure to the nocturnal

air.