TITE POPULAR EDUCATOR. 



set off the spaces z a, a b, etc., z a', a' b', etc., six on one side 

 and six on the other : the straight lino C D, which is composed 

 of twelve of these equal parts, will represent the equator, on 

 either side of which the gores are to be formed, and be exactly 

 equal to the equatorial circumference of the pasteboard sphere. 

 Through c, z, and D, draw the straight lines K F, x Y, Q H, at 

 right angles to A B. From c, on either side of A B, along c E 

 and C P, set off C M, C K, each equal to three times z a, or half z c ; 

 and from D, along D H, D Q, set off D L, D N, each equal to half z c. 

 Join K L, M N ; then K M N L ia a parallelogram of which the 

 length c D or M N is equal to twice the breadth M K ; and in the 

 lines K L, M N, the points forming the extremities of the gores 

 should fall, or the arcs which form either side of each gore 

 intersect. 



To draw the gores, it is first necessary to obtain a line as a 

 radius with which the arcs containing them may be described. 

 The radius of the arcs is equal to nine and a-half times z a, or D o, 

 or c v ; and may be readily determined by bisecting c d or d d', 

 (the tenth space numbering from D or c) in o or v. With this 

 radius, from centres on the line z A produced indefinitely towards 



or better, with, a radius of 25, which will leave room for the 

 delineation of the arctic and antarctic circles with a margin 

 boyond them. 



The gores and circles should be drawn on thin but very tough 

 paper, and the coast-lines, rivers, mountains, etc., should bo 

 carefully sketched in Indian ink, and the lettering inserted as 

 far aa possible. They should then be damped and pasted on 

 the sphere, care being taken to fit the gores together with exact- 

 ness, so that the arcs forming tho parallels may all meet. In 

 pasting on the gores, the meridians drawn on the surface of the 

 sphere will be found useful as guide-lines to fix the position of 

 the gores. When thoroughly dry the lettering must be com- 

 pleted, and the land, water, etc., must be coloured, a coat of 

 two of white varnish being added as a finish. The globe thus pre- 

 pared must be fixed in a brass meridian circle properly gra- 

 duated, and the whole suspended in a wooden frame, the upper 

 part of which is a circle to represent the horizon, and what 

 is called the wooden horizon. This is covered with paper 

 graduated to show the succession of the months, relative time at 

 different parts of the earth's surface, etc. etc. 



A, describe arcs through the points D, ef, d', etc., as far as e ; and 

 through the points c, e, ct, etc., as far as e', describe arcs with 

 the same radius from centres in z B produced indefinitely towards 



B. Thus o will be the centre of the arc passing through D, and 

 Q the centre of the arc y y' passing through c ; and in the same 

 manner v will be the centre of the arc passing through c, and P 

 the centre of the arc x x' passing though c. To draw the parallels 

 of latitude in each gore, join the extremities as a; a;' or y y', and 

 divide this straight line into nine equal parts, each containing 10, 

 on either side of the equator, and through the points thus found 

 draw arcs from x, a/, y, y', as centres, as shown in the diagram. 

 To draw the meridians, divide the equatorial parallel in each 

 gore, as Z> c or 6' c', into three equal parts of 10 each, also trisect 

 the third arc from the equator, and the third arc from the ex- 

 tremity in each half-gore, and form the meridians by dra'wing 

 curved lines through the extremities of each gore, and the jive 

 intermediate points determined by the trisection of the equa- 

 torial parallel and four arcs of latitude. 



Although the whole of the gores should be drawn for the pur- 

 pose of determining the extremities as centres from which to 

 describe the arcs that form the parallels of latitude, the deli- 

 neation of coast-line, etc., need not be carried above lines drawn 

 through R, s, and T, u, a little above the arctic circle. Circles 

 to finish the top and bottom of the globe may then be drawn on 

 a separate piece of paper, as shown at x with a radius of 231, 



We now pass on to the method of drawing a projection of 

 any small part of the earth's surface that we may wish to de- 

 lineate on a large scale. Suppose Italy were the country of 

 which we wished to make a map, using the conical form of pro- 

 jection, and that we desired to draw it on the scale of 1 inch to 

 60 geographical miles, or a degree of the equator, it is manifest 

 that to describe the arcs forming the parallels of latitude from 

 a common centre, as in the projection for the map of Europe 

 (Vol. II., p. 356), we should require to find a point distant, 

 approximately speaking, about 5 feet from the point through 

 which the arc representing the parallel of 36 north latitude 

 must be described. It would be inconvenient to do this unless 

 we were provided with beam compasses and a flat table of great 

 length. Let us see, then, how we can construct a projection by 

 the aid of ordinary compasses only, and yet preserve the curved 

 form and parallelism of the arcs representing the parallels of 

 latitude, giving each its proper degree of curvature. 



As Italy covers pretty much space for our purpose, and as in 

 naming Italy we merely wished to call attention to the great 

 length of the radii required for desc-ibing the arcs representing 

 the parallels of latitude from a common centre, in delineating 

 any of the southern countries of Europe, we will take Scotland, 

 which lies the Orkney Islands being included between the 

 parallels of 54 30' and 59 30' north latitude. First of all draw 

 a perpendicular straight line A B (Fig. 22), and through c, a point 



