Chamber of Commerce, that relative efficiency being considered, the cost of labour (including the labour of supervision) in Bombay and Lancashire was about equal, and that the wages of Indian operatives increased with their efficiency. We may hope, therefore, that in the future the greater human energy of the temperate zone will be the true correlative of the greater productiveness of the tropics; that the two zones will prove permanently complementary to one another; that, as the products of the tropics are indispensable to the inhabitants of the temperate zone, so certain products of the temperate zone will remain indispensable in the tropics. Sir William Hunter himself points out that India seems, with the growth of her own manufactures, to have an ever-growing fund for the purchase of goods in England, and he anticipates that in the end the development of the industrial era in India will be a gain to Britain in common with the whole world.

Space forbids our entering at any length on the other tropical parts of the empire in the Old World, and to do so would indeed be superfluous for the purpose now in view. The fluctuations in the trade with Ceylon bear witness to the vicissitudes affecting the coffee, tea, cinchona, and other plantations of the colony; those in the trade with the Straits Settlements afford similar evidence as to the fluctuations in the tin industry of the Malay States, and the entrepôt trade of Singapore. Though the trade of Mauritius with the United Kingdom is relatively small, that trade, nevertheless, furnishes a good illustration of the saying, "Trade follows the flag," inasmuch as the great bulk of it is with other British possessions, principally India and Australasia. From the Mauritius India derives annually from 50,000 to 60,000 tons of sugar, or even more, and yet it receives only a trifling quantity of any product from the neighbouring island of Réunion, which is all the more striking since it supplies to both islands the bulk of the rice consumed by the plantation labourers. As regards our new protectorate and "sphere of influence" in East Africa, it would require an entire paper to investigate the prospects of trade there, and it is all the less necessary for me to attempt that here, since it has already been dealt with on several occasions in this magazine.

Our diagrams show the relative importance of our trade with our principal tropical possessions in the New World-the British West Indies and Guiana. It is a trade that has suffered more or less in recent years through the competition of foreign countries, stimulated by sugarbounties. Till recently the trade with the United Kingdom held the first place the commerce of the principal colonies, but of late years the growth of the export of sugar from many of them and of fresh tropical fruits (principally bananas) from Jamaica to the United States has caused the latter country to rise to the first place among those receiving the exports of Jamaica and Barbados as well as some of the minor islands. This trade is obviously greatly favoured by the geographical conditions, and it can hardly be doubted that it will tend to grow in the future.

1 See the Report of this Inquiry, paragraphs 529 and 154-61.

HOW MAPS ARE MADE.

BY W. B. BLAIKIE.

(Read at Meetings of the Society in Edinburgh and Glasgow, April 1891.) THE subject on which I am deputed to address you to-night is what in the slang of the day may be described as "a very large order." Though the title seems simple enough, the subject itself is so large, and it spreads and ramifies itself through so many arts and sciences, that the temptation to go off from the distinct line of my subject into the different branches that introduce themselves is great, and all these branches are to me so interesting, that I have found great difficulty in confining myself strictly to the story of how a map is made. I have forced myself, however, to stay on the centre line of map-making, and I hope, before the evening is over, to give you a clear and distinct idea of the principles on which a map is made, for the subject of my paper is not "How Maps are Drawn," but "How Maps are Made"; and I will attempt to show you the naked machinery of the process.

I have often been amazed at the popular ignorance of what would seem to be the very first principles of geography and of map-making, and this has induced me to begin at the very A B C of the subject. I intend throughout this paper to avoid technical phrases and mathematical terms. I have nothing new to tell you; much that I am about to say is known to every person here present, and I ask you to bear with me if occasionally I seem childish in my descriptions.

One thing more I should like to premise, and that is, that in this paper I do not propose to go into any great detail, or to confuse any one here with the numberless scientific corrections and modifications that have to be made in all scientific calculations. I will only speak on general principles; those who know the science thoroughly will understand the modifications necessary, while those who have not the same advantage will, I trust, be able to grasp the principles of what is shown.

My intention to-night is to show (1) how a spectator finds his position on the earth's surface; (2) how he defines and records that position; (3) how he makes a map from the information he has found; (4) how he fills up the details of that map; and (5) briefly to describe how the map so made is drawn and printed, and incidentally to show the use of the various tools and instruments employed in these operations.

I assume that we all know that the earth is (roughly speaking) a sphere, spinning round on its axis once in twenty-four hours. Now, if we take up a sphere, like this ball, and mark a spot on it, there is nothing whatever to define its position: no north, no south; nothing to guide us. One point on this sphere is the same as any other point, until we find some reference spot to measure from; but we have assumed that we know that the earth spins round on its axis, and here we at once discover something we can measure from. The ends of the axis of the ball, which we call the poles, are, we see, at rest compared with the rest of the surface of the spinning ball.

Now, this so-called polarity gives us at once two points of reference. Although no one has ever been at either of the Poles, the study of the subject for hundreds of years has proved their existence as surely as if the Poles had been visited and been discovered marked with upstanding posts. Between these two points, which we call the Poles, I can mark a point half-way, which, by spinning the ball in contact with the pencil, I convert into a line-called the Equator, the equal divider-popularly the Line. You will observe that this middle line-this Equator-is also the largest possible circle on this sphere, and it is from this circle that all measurements and references North and South are made. see on the globe and on maps a number of other circles parallel to the Equator to the north and south of it, and drawn at equal distances. These are called the parallels of Latitude (or wideness), and they mark certain degrees of angular divergence from the Equator.

We

Consider for a moment what this means. In the first conception of them these lines have no specific distance apart, because they really are angular measurements, and it is this conception of them I wish you to get hold of.. A degree of latitude is not necessarily a number of miles, and until we know the actual diameter of the earth we cannot tell what the length of a degree is. It is a proportion of the circumference of a circle-a fractional measurement of it. We may speak of a half, a quarter, of anything, but, until we say what it is a half of or a quarter of, the phrase conveys no idea of magnitude. It might be half a mile, or half a kingdom, or half an inch, or half a crown. Similarly, a degree of a circle means nothing so far as length is concerned, until you know the size of the circle, when you can at once calculate, with the proper mathematical knowledge, the numerical value of a degree at the Earth's circumference.

Now, having marked these lines on the surface of the Earth, we have certain marks on our globe to which we can refer any and every point. It may be said, "Why mark these lines on the map? They do not exist; they are only imaginary." Quite true! But then the first principle of all map-making is to begin with imaginary lines, from which to measure the position of every place on that map; and all such imaginary lines are carefully recorded, as we shall see later on, so that they can be accurately laid down at any moment by those who know how to find them. We find them a great convenience-an absolute necessity indeed-so we leave them drawn on the globe. Imagine a street -any street will do, but for a good analogy imagine a street built, like Moray Place, in a circle. We can say, speaking of, say, a waterplug, or any point in that street, that it is on the centre line of the street, or the line of the lamp-posts, or so many feet to one side of either of these lines. There is no visibly marked centre line or line of lamp-posts, but it can be filled up in a moment by human intelligence, and if there were to be frequent references to them these lines would be marked on a plan for constant use. The parallels of latitude are similar lines drawn for convenience of reference.

The circumference of the Earth, like any other circle, is divisible into 360 degrees, and we number the parallels by the number of degrees of

angular divergence; only, instead of beginning at a pole and going right round, we, for convenience' sake, begin at the Equator and then number 90 degrees towards the North Pole and 90 degrees towards the South Pole.

But one set of reference lines is not enough; we must have another set, and we get them in the meridians of Longitude. We draw these through the poles, at right angles to the Equator. They are all "great circles"; that is, each circle is concentric with the globe. The Equator being a circle, we divide it as before into 360 degrees, and the meridians through the points of section form a second system of lines of reference. But, unlike the parallels of latitude, they are all the same size. One is the same as another. How are they to be numbered? Go back for a moment to Moray Place, and remember the lines we drew-the centre of the street, and the line of the lamp-posts. How are we to define a spot on one of these lines? They are circular, and consequently have no beginning and no end. What we should do would be to mark a convenient spot with a flag, or a peg, or a stone, and say—"That is the beginning; measure from that."

This is exactly what we must do in longitude. We must mark a starting line on the earth, and call it Zero; and as all nations have a free choice they have not chosen the same. We have chosen the meridian of Greenwich, the French that of Paris, the Americans Washington, and the Russians Pulkova and the Germans used to use Ferro; but for all English maps, and now for most foreign ones, the meridian of Greenwich is the starting line-the Zero of longitude.

The custom here again is not to reckon 360 degrees round the circle, but to reckon 180 degrees east and 180 degrees west. We saw that latitude was angular divergence from the Equator; but what are these degrees of longitude? Look at a ball spinning round opposite a candle. We assumed a knowledge that the earth spun round its axis in 24 hours. Every part of it comes in turn opposite a heavenly body (say the sun) once in 24 hours, just as every part of this ball comes opposite the candle once in each revolution. Longitude is, then, angular divergence measured by the difference of time in coming opposite a heavenly body. As the circle is divisible into 360 degrees, so the day, i.e. the revolution of the earth, is divisible into 24 hours, and one hour of longitude is consequently equal to 15 degrees. In maps longitude is marked in degrees, while in almanacs the elements given to reckon it are always written in hours, minutes, and seconds.

Remember, once more, that these degrees are not lengths measured on the surface, but are the record of angular divergence from the initial meridian. It is all the more necessary to bear this in mind because the length on the surface of the Earth of a degree of longitude varies enormously, being greatest at the Equator and nothing at all at the Pole, differing thus from degrees of latitude, which, roughly speaking and for the purposes of this paper, may be considered equal.

The idea that latitude and longtitude are the measures of angular divergence and not absolute distance in miles or yards may be easily grasped by a familiar illustration. If you can imagine two travellers

leaving Italy by road, the one over the St. Gothard pass, and the other over Mt. Cenis, and two other travellers following them by rail at such an interval of time that they are in the railway tunnels at exactly the same moment that the pedestrians attain the summits of the passes: the pedestrian on the mountain and the railway traveller in the tunnel of the St. Gothard pass will be in exactly the same latitude and longitude, and so will the travellers by the Mt. Cenis routes. The pedestrians, however, will be about sixty yards further apart from each other than the railway travellers. The reason of this of course is, that the pedestrians are further away from the Earth's centre, but their angular divergence from the Equator and the Earth's axis are precisely the same, whether they are on the mountain or in the tunnel 5000 feet below.

Now, having defined latitude and longitude and shown how the lines representing them are drawn, we must see how in practice the surveyor finds the latitude and longitude of a place, and thereby begins his map. The Poles, as we saw, are first points to measure from, and the Equator the half-way line. It is evident he cannot measure directly a line from Pole to Pole, find out the half and call it the Equator, and leave pegs at each parallel in passing. He must look to things outside the Earth itself from which to reckon, and he gets such reference-points in the heavenly bodies. To his eye these are situated in the great vault of the heavens. He sees them as if on the surface of a hollow globe continually revolving around him, rising in the east till they reach their highest point above him, called the culminating point, then setting in the west. For thousands of years astronomers have studied these bodies, and fixed their apparent positions in the celestial vault; and these positions are recorded with the utmost possible accuracy in a book compiled by Government, called the Nautical Almanac, and from the practical information given there the surveyor finds his position. He may take the sun, or he may take the stars; but the positions of the sun being affected by the motion of the earth round it, I propose to take a star to illustrate my next remarks, as its movements are simpler.

The pole of the heavens is the end of the axis of the earth infinitely prolonged. The intersection of the plane of the Equator with the celestial vault is called the Equinoctial; and as the angular divergence on the surface of the Earth is measured in degrees from the Equator and called Latitude, so the angular divergence of a heavenly body from the Equinoctial is called its Declination. As the angular divergence from the meridian of Greenwich was called Longitude, so the divergence in time from a starting-point in the heavens is called Right Ascension. We had to fix arbitrarily the meridian of Greenwich as a starting-line on the Earth. We have also to fix equally arbitrarily a starting-point in the heavens, and that point may be most simply described as the point in the heavens in which the sun is in spring, when the day and night are equal.

The latitude of any place on the earth's crust is equal to the altitude of the celestial pole. You can see this in a moment if you imagine yourself on the Equator and look to the pole, marked, say, by the Pole Star. You will see it on the horizon and of no altitude at all; and at the Equator you have no latitude, or it is called Zero, but, as you approach the