Notes on Map Projections. 337 
_ If we conceive this projection extended to include the entire 
earth, a singular result appears. ‘Taking the equator as the cen- 
proaches that of the developed equator. It will be seen that 
each parallel falls nearer the equator than it would in Flamstead’s 
projection, being, indeed, tangent on the equatorial side of the 
Flamstead perpendicular. ‘Thus, in this method the projected 
area is less than that of the spheroidal surface. If an equidistant 
parallels much too long; giving a grotesqueness to the polar re- 
gions bordering on that of a Mercator projection. The scale be- 
spheroid, and still great even in a map of the United States, it is 
clear that the polyconic-equidistant projection ought by no means 
to be extended beyond the most moderate limits. A square de- 
gree, on a scale of --1-., may be taken as a limit, beyond which 
ho convenience of graphic construction should induce the use of 
Coast Survey office, and tables, prepared for facilitating its use, 
ag there computed, and are now first published in the Report 
or 1853. 
GRAPHIC CONSTRUCTION OF POLYCONIC PROJECTIONS—COAST SUR- 
VEY M 
Having fixed the limits to be covered by the projection, the 
Central meridian is represented by a straight line, as nearly as 
practicable, through the centre of the sheet. From an assumed 
starting-point on this line are laid off the successive meridian 
Through each point of division on the central meridian, given 
by these tabular ares, erect a perpendicular to it by means of a 
Szcoxp Series, Vol. XVIII, No. 54.—Nov., 1854. 3 
