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LX XI II. Of the heft Form of Geographical 
Maps. By the Rev. Patrick Murdoch, 
M.A. F.R.S. 
Read Feb. 9, I. T T T H E N any portion of the earth’s 
l/ S 8 - VV furface is projected on a plane, 
or transferred to it by whatever method of defcrip- 
tion, the real dimenfions, and very often the figure 
and pofition of countries, are much altered and mif- 
reprefented. In the common projection of the two 
hemifpheres, the meridians and parallels of latitude 
do indeed interfeCt at right angles, as on the globe ; 
but the linear diftances are every- where dimi- 
niflied, excepting only at the extremity of the pro- 
jection : at the center they are but half their juft 
quantity, and thence the fuperficial dimenfions but 
one-fourth part k and in lefs general maps this in- 
convenience will always, in fome degree, attend the 
fiereographic projection. 
The orthographic , by parallel lines, would be ftill 
lefs exaCt, thofe lines falling altogether oblique on 
the extreme parts of the hemifphere. It is ufeful, 
however, in defcribing the circum- polar regions : and 
the rules of both projections, for their elegance, as 
well as for their ufes in aftronomy, ought to be re- 
tained, and carefully ftudied. As to Wright’s, or 
Mercator’s, nautical chart, it does not here fall un- 
der our confideration : it is perfeCt in its kind ; and 
will always be reckoned among the chief inventions 
of the laft age. If it has been mifunderftood, or 
mifapplied, by geographers, they only are to blame. 
Vol. 50. 4B II. The 
