272 GEOGRAPHY AND ASTRONOMY. longitude marked on the same parallel of latitude are unequal, and so the degrees of latitude marked on the same meridian are often unequal. (See the XI. section concerning maps.) The only way therefore of measuring distances on a map is to mea- sure the number of degrees on the nearest correspondent line of longitude or latitude, and apply that to the distance required, which after all is but an uncertain account. Problem IV. " To find the antraci, periceci and antipodes of any place given, suppose of London." Bring London to the meridian, observe its latitude north- ward, then reckon so many degrees on the meridian from the equator southward, and it shews the placeof the líntceci. Keep London under the meridian, set the hour index or pointer on the dial at the pole to the upper 12 which is 12 o'clock at noon, turn the globe about till the index point to 12 at midnight, and the place that will be under the same degree of the meridian where London was, shews where the periæci dwell. The globe so standing, count the same degrees of latitude from the meridian southward, and that will shew who are the antipodes to London. Problem V. " Any place being given to find all those places which have thesame hour of the daywith that in the given place." All the places that have the same longitude have the same hour. Bring the given place therefore to the brazen meri- dian, and observe what places are then exactly under the graduated edge of the meridian, for the people in those pla- ces have the same hour, and their habitation has the same longitude. Problem VI. " Any place being given (suppose Paris to find all those places in the world which have the same latitude, and consequently have their days and nights of the same length." Bring Paris to the meridian, and yeti find it near 49 degrees north latitude. Turn the globe all round, and all those places which pass under the 49th degreeof the meridian have the same latitudewith Paris, and the pole is just as much elevated above' their horizon, viz. 49 degrees. ProblemVII. f° To rectify the globe according to the lati- tude of any given place." Elevate the proper pole (whether it be north or south) so far above the horizon as is the latitude of the place proposed ; this is done by moving the pole of the globe upward from the horizon, counting by the degrees of the under part of the meri- dian, which begin to be numbered from the pole ; thus for Lon- don you must raise the pole 51l degrees above thehorizon,
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