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every thing is frozen so long as the sun is under the horizon, or but a little above it. However, these zones are, not quite uninhabitable, though much less fit for living in than the torrid.
None of all thefe zones are thoroughly discovered by the Europeans. Our knowledge of the fouthern temperate zone is very imperfect; we know little of the northern frigid zone; and still less of the southern frigid zone. The northern temperate and torrid zones are those we are best acquainted with.
CLIMATES.] But the division of the earth into hemispheres and zones, though it may be of advantage in letting us know in what quarter of the carth any place lies, is not fufficiently minute for giving us a notion of the diftances between one place and another. This however is still more neceffary, because it is of more importance to mankind to know the situations of places with regard to each other, than with regard to the earth itself.
The first step taken for determining the relative situation of places was to divide the earth into what are called Climates. It was observed, that the day was always twelve hours long at the equator, and that the longest day increased in proportion as we advanced north or fouth on either side of it. The ancients therefore determined how far any place was north or fouth of the equator, or what is called the Latitude of the place, from the greatest length of the day in that place. They conceived a number of circles parallel to the equator, which bounded the length of the day at different distances from the equator; and as they called the spaces contained between these circles Climates, because they declined from the equator towards the pole, so the circles themselves may be called Climatical Parallels. This, therefore, was a new division of the earth, more minute than that of zones, and still continues in use; though, as we ihall show, the design which first introduced it may be better answered in another way. There are thirty climates between the equator and either pole. In the first twentyfour, the days increase by half
hours: but in the remaining fix, between the polar circle and the pole, the days increase by months. The nature and reason of this the reader will more fully understand, when he becomes acquainted with the use of the globe : in the mean time, we shall infert a table, which will serve to show in what climate any country lies, fuppofing the length of the day, and the distance of the place from the equator, to be known.
QUADRANT OF ALTITUDE.), In order to supply the place of the con passes in this operation, there is commonly a pliant narrow plate of braf: screwed on the brazen meridian, which contains ninety degrees, or on quarter of the circumference of the globe, by means of which the distances and bearings of places are measured without the trouble of first extending the compafles between them, and then applying the same to the equator. This plate is called the Quadrant of Altitude.
Hour CIRCLE.] This is a small brafs circle fixed on the brazen me. ridian, divided into twenty-four hours, and having an index moveable round the axis of the globe.
29 28 27 26
1 2 3 4 5 6 7 8 9 10
96 94 92 86 77 67 56 40
61 62 63 64 65 66 67 68 69 70 71 72 73
74 15 54 92 28 62 00) 28 95 88 16 43
30 36 41 45 4S 51 52 54
59 59 59 59 59 59 59 59 59 59 58 58 58 58 58 57 57 57 56 56 56 55 55 54
12 13 14
34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 33 54 55 56 57 58 59
16 17 18 19 20 21 22 23 24 25 26
75 76 77 78 79 80 31 82 83 84 85
54 53 52 51 50 48 45 42 38 35 32 28 23 18
15 14 13 12 11 10 09 08 07 06 05 04 03 (2 01 00
36 35 34 33 32 31 30
53 53 52 51
09 05 00
LATITUDE.] The distance of places from the equator, or what is called the Latitude, is easily measured on the globe, by means of the meridian above described. For we have only to bring the place, whose latitude we would know, to the meridian, where the degree of latitude is marked, and it will be exactly over the place. As latitude is reckoned from the equator towards the poles, it is either northern or fouthern; and the nearer the poles, the greater the latitude. No place can have more than ninety degrees of latitude, because the 'poles, where the reckoning of the latitude terminates, are at that distance from the equator.
PARALLELS OP LATITUDE.] Through every degree of latitude, or, more properly, through every particular place on the earth, geographers fuppose a circle to be drawn, which they call a parallel of latitude. "The intersection of this circle with the meridian of any place shows the true fituation of that place.
LONGITUDE.) The Longitude of a place is its situation with regard to the first meridian, and consequently reckoned towards the east or weft: in reckoning the longitude, there is no particular spot from which we ought to set out preferably to another ; but, for the advantage of a general rule, the meridian of Ferro, the most westerly of the Canary islands, was formerly consdered as the first meridian in most of the globes and maps, and the longitude of places was reckoned to be so many degrees east or west of the meridian of Ferro. The modern globes fix the first meridian, from which the degrees of longitude are reckoned, in the capital city of the different countries where they are made, viz. the English globes date. the first meridian from London or Greenwich, the French globes from Paris, &c. The degrees of longitude are marked on the equator. No place can have more than 180 degrees of longitude, because, the circumierence of the globe being 360 degrees, no place can be remote from another above half that dittance; but many foreign geographers improperly reckon the longitude quite round the globe. The degrees of longitude are not equal, like those of latitude, but diminish in proportion as the meri. dians incline, or their distance contracts in approaching the pole. Hence, in fixty degrees of latitude, a degree of longitude is but half the quantity of a degree on the equator, and so of the rest. The number of miles contained in a degree of longitude in each parallel of latitude, are set down in the table in the following page.
LONGITUDE AND LATITUDE FOUND.) To find the longitude and latitude of any place, therefore, we need only bring that place to the brazen meridian, and we shall find the degree of longitude marked on the equator, and the degree of latitude on the meridian. So that to find the distance between two places in the same latitude, we have only to subtract the greater longitude from the less, and the difference, reduced to miles, according to the table given below, will be the distance fought. If the places have the same longitude, the difference of latitude turned into miles at the rate of 60 geographic or 694 English statute miles to a degree, will give the distance.
DISTANCE OF PLACES measured.] The distance of places which lie in an oblique direction, i. e. neither directly south, norih, east, nor west, from one another, may be measured by extending the compasses from the one to the other, and then applying them to the equator. For instance, extend the compasses from Guinea in Africa, to Brazil in America, and then apply them to the equator, and you will find the distance to be twenty-five degrees, which, at fixty miles to a degree, makes the distance 1500 miles,
QUADRANT OF ALTITUDE.] In order to supply the place of the con paffes in this operation, there is commonly a pliant narrow plate of bra screwed on the brazen meridian, which contains ninety degrees, or on quarter of the circumference of the globe, by means of which the difiance and bearings of places are measured without the trouble of first extending the compasses between them, and then applying the same to the equator This plate is called the Quadrant of Altitude.
HOUR CIRCLE.] This is a small brafs circle fixed on the brazen ridian, divided into twenty-four hours, and having an index moveable round the axis of the globe.
61 62 63
18 17 16 15
04 17 24 30 36 41 45 4S 51 52 54 55 54 53 52 31 50 48 45 42 38 35 32 28 23 18 14 09 05 00
59 59 58 58 58 58 58 57 57 57 56 56 56 55 55 54
77 78 79 80) 81 82 83 84 85 86 87
13 12 11 10 09 08 07 06 05 04 03 (2 01 00
PROBLEMS PERFORMED BY THE GLOBE.
its Surface in square, and its Sólidity in cubic, Measuré. MULTIPLY the diameter by the circumference, which is a great circle dividing the globe into two equal parts, and the product will give the first : then multiply the said product by one fixth of the diameter, and the product of that will give the second. After the fame manner we may find the surface and folidity of the natural globe, as alfu of the whole body of the atmosphere surrounding the same, provided it be always and every where of the lame height; for, having found the perpendicular height of the atmosphere by the common experiment of the ascent of mercury at the foot and top of a mountain, doable the faid height, and add the same to the diameter of the earth ; then multiply the whole, as a new diameter, by its proper circumference, which again niultiply by one fixth of that diameter, and from the product fubtract the solidity of the earth, it will leave that of the atmosphere.
Prob. 2. To re&tify the Globe.
PROB. 3. To find the Longitude and Latitude of any Place.
that Place on the Globe.
Places that have the same Latitude. The globe being rectified (a) according to the latitude of the given place, and that place being brought to the ray Prob. 2. brazen meridian, make a mark exactly above the same, and turning the globe round, all those places paffing under the said mark have the same latitude with the given place.
Prob. 6. To find the Sun's Place in the Ecliptic at any Time.
Time of that Day, to find those Places of the Globe to which the