1. After these criticisms on the writers who have preceded us, we must now confine our attention to the fulfilment of our promise. We start with a maxim we laid down at the commencement, that whoever undertakes to write a Chorography, should receive as axioms certain physical and mathematical propositions, and frame the rest of his work in accordance with, and in full reliance on, these principles. We have already stated [our opinion], that neither builder nor architect could build house or city properly and as it ought to be, unless acquainted with the clima of the place, its position in respect to celestial appearances, its shape, magnitude, degree of heat and cold, and similar facts; much less should he [be without such information] who undertakes to describe the situation of the various regions of the inhabited earth.
Represent to the mind on one and the same plane-surface Iberia and India with the intermediate countries, and define likewise the west, the east, and the south, which are common to every country. To a man already acquainted with the arrangement and motions of the heavens, and aware that in reality the surface of the earth is spherical, although here for the sake of illustration represented as a plane, this will give a sufficiently exact idea of the geographical [position of the various countries], but not to one who is unacquainted with those matters. The tourist travelling over vast plains like those of Babylon, or journeying by sea, may fancy that the whole country stretched before, behind, and on either side of him is a plane-surface; he may be unacquainted with the counter-indications of the celestial phenomena, and with the motions and appearance of the sun and stars, in respect to us. But such facts as these should ever be present to the mind of those who compose Geographies. The traveller, whether by sea or land, is directed by certain common appearances, which answer equally for the direction both of the unlearned and of the man of the world. Ignorant of astronomy, and unacquainted with the varied aspect of the heavens, he beholds the sun rise and set, and attain the meridian, but without considering how this takes place. Such knowledge could not aid the object he has in view, any more than to know whether the country he chances to be in may be under the same latitude as his own or not. Even should he bestow a slight attention to the subject, on all mathematical points he will adopt the opinions of the place; and every country has certain mistaken views of these matters. But it is not for any particular nation, nor for the man of the world who cares nothing for abstract mathematics, still less is it for the reaper or ditcher, that the geographer labours; but it is for him who is convinced that the earth is such as mathematicians declare it to be, and who admits every other fact resulting from this hypothesis. He requests that those who approach him shall have already settled this in their minds as a fact, that they may be able to lend their whole attention to other points. He will advance nothing which is not a consequence of these primary facts; therefore those who hear him, if they have a knowledge of mathematics, will readily be able to turn his instructions to account; for those who are destitute of this information he does not pretend to expound Geography.
2. Those who write on the science of Geography should trust entirely for the arrangement of the subject they are engaged on to the geometers, who have measured the whole earth; they in their turn to astronomers; and these again to natural philosophers. Now natural philosophy is one of the perfect sciences.704
The “perfect sciences” they define as those which, depending on no external hypothesis, have their origin, and the evidence of their propositions, in themselves. Here are a few of the facts established by natural philosophers.705
The earth and heavens are spheroidal.
The tendency of all bodies having weight, is to a centre.
Further, the earth being spheroidal, and having the same centre as the heavens, is motionless, as well as the axis which passes through both it and the heavens. The heavens turn round both the earth and its axis, from east to west. The fixed stars turn round with it, at the same rate as the whole.706 These fixed stars follow in their course parallel circles; the principal of which are, the equator, the two tropics, and the arctic circles. While the planets, the sun, and the moon, describe certain oblique circles comprehended within the zodiac. Admitting these points in whole or in part, astronomers proceed to treat of other matters, [such as] the motions [of the stars], their revolutions, eclipses, size, relative distance, and a thousand similar particulars. On their side, geometers, when measuring the size of the entire earth, avail themselves of the data furnished by the natural philosopher and astronomer; and the geographer on his part makes use of those of the geometer.
3. The heavens and the earth must be supposed to be divided each into five zones, and the celestial zones to possess the same names as those below. The motives for such a division into zones we have already detailed. These zones may be distinguished by circles drawn parallel to the equator, on either side of it. Two of these will separate the torrid from the temperate zones, and the remaining two, the temperate from the frigid. To each celestial circle there shall be one corresponding on earth, and bearing the same name, and likewise zone for zone. The [two] zones capable of being inhabited, are styled temperate. The remaining [three] are uninhabitable, one on account of the heat, the others because of the extreme cold. The same is the case with regard to the tropical, and also to the arctic circles, in respect of those countries for which arctic circles can be said to exist. Circles on the earth are supposed, corresponding to those in the heavens, and bearing the same name, one for one.
As the whole heaven is separated into two parts by its equator, it follows that the earth must, by its equator, be similarly divided. The two hemispheres, both celestial and terrestrial, are distinguished into north and south. Likewise the torrid zone, which is divided into two halves by the equator, is distinguished as having a northern and southern side. Hence it is evident that of the two temperate zones, one should be called northern, the other southern, according to the hemisphere to which it belongs. The northern hemisphere is that containing the temperate zone, in which looking from east to west, you will have the pole on your right hand, and the equator on the left, or, in which, looking south, the west will be on the right hand, and the east on the left. The southern hemisphere is exactly the contrary to this.
It is clear that we are in one or other of these hemispheres, namely, the north; we cannot be in both:
“Broad rivers roll, and awful floods between,
But chief the ocean.”707
And next is the torrid zone. But neither is there any ocean in the midst of the earth wherein we dwell, dividing the whole thereof, nor yet have we any torrid region. Nor is there any portion of it to be found in which the climata are opposite to those which have been described as characterizing the northern temperate zone.
4. Assuming these data, and availing himself likewise of astronomical observations, by which the position of every place is properly determined, whether with respect to the circles parallel to the equator, or to those which cut these latter at right angles, in the direction of the poles, the geometer measures the region in which he dwells, and [judges of the extent of] others by comparing the distance [between the corresponding celestial signs]. By this means he discovers the distance from the equator to the pole, which is a quarter of the largest circle of the earth; having obtained this, he has only to multiply by four, the result is the [measure of the] perimeter of the globe.
In the same manner as he who takes the measures of the earth, borrows the foundation of his calculations from the astronomer, who himself is indebted to the natural philosopher, so in like manner the geographer adopts certain facts laid down as established by the geometer, before setting forth his description of the earth we inhabit; its size, form, nature, and the proportion it bears to the whole earth. These latter points are the peculiar business of the geographer. He will next enter on a particular description of every thing deserving notice, whether on land or sea; he will likewise point out whatever has been improperly stated by those who have preceded him, especially by those who are regarded as chief authorities in these matters.708
5. Let it be supposed that the earth and sea together form a spheroidal body, and preserve one and the same level in all the seas. For though some portions of the earth may be higher, yet this bears so small a relation to the size of the whole mass, as need not be noticed. The spheroid in consequence is not so minutely exact as one might be made