Penfield — Use of the Stereographic Projection, etc. 347 



Art. XXX. — On the Use of the Stereographic Projection 

 for Geographical Maps and Sailing Charts/ by S. L. 

 Penfield. 



[Continued from p. 275.] 



Stereographic Map of the United States. — A much reduced 

 copy of the map made by the writer is shown in figure 21, and 

 it should be said regarding it that it was drawn solely for the 

 purpose of making a practical test of the accuracy with which 

 measurements may be made with a scale of miles on such a 

 projection, therefore not much detail is shown. As far as 

 may be told by the eye, the map does not give the impres- 

 sion of being different from others with which we may be 

 accustomed, but, owing to the fact that it is stereographic and 

 so projected as to show minimum distortion, it is believed that 

 it is the best kind of a map, embracing so large an extent of 

 country, which can be made. The cities shown on the map 

 were located from the following data, mostly taken from the 

 Encyclopaedia Britannica : 



Albany, N. Y. 

 Baltimore, Md. 



42 c 

 39 



W 



Boston, Mass. 42 21£ 



Buffalo, N. Y. 42 53 



Chicago, 111. 41 50 



Columbus, 0. 39 57 



Denver, Colo 39 45 



Duluth, Minn. 46 48 



Hartford, Conn 41 46 



Helena, Mont 46 35| 



Indianapolis, Ind. 39 47 



Key West, Fl 24 41 



Lansing, Mich. 42 46£ 



Lincoln, Neb. 40 55 



Nashville, Tenn. 36 10 



New Haven, Conn. 48 18i 



New Orleans, La 29 55 



New York, N. Y 40 43 



Longitude- 



73° 32' 



76 37 



71 4 

 78 55 

 87 34 



83 3 

 105 00 



92 6 



72 40f 

 111 52| 



86 6 



81 46 



84 32f 

 96 52 

 86 49 

 72 56* 

 90 00 

 74 00 



Olympia, Ore 



Philadelphia, Pa 



Portland, Me. .. 



Portland, Ore 



Pt. Isabel, Tex. 



Raleigh, N. C. 



Richmond, Va. __ T 



San Diego, Cal. 



San Francisco, Cal 



Springfield, 111. 



St. Augustine, Fl. 



St. John, New Brunswick 



St. Louis, Mo. 



St. Paul, Minn 



Trenton, N. J. 



Vancouver, B. C 



Washington, D. C 



Latitude. 



47° 3' 



39 57 



43 39 

 45 30 

 26 5 

 35 47 

 37 32i 

 32 44 



37 47 

 39.48 

 29 49 

 45 17 



38 37* 



44 52f 



40 14 

 49 18 

 38 53i 



Longitude. 



122° 57' 



75 10 



70 15 



122 27 



97 5 



78 48 



77 27* 



117 8 



122 25 



89 33 

 81 16 

 66 5 



90 15 

 93 5 

 74 46* 



123 6 

 77 00* 



To locate places with accuracy a sliding scale, figure 22, may 

 be used to advantage. It consists of a system of equally 

 spaced, diverging lines, drawn on some transparent material 

 such as tracing cloth or parchment paper. To locate Indian- 

 apolis, 39° 47' N., 86° 6' W., for example; on the nearest 

 meridians, 85° and 87°, the approximate latitude is marked 

 with a soft pencil, and the scale is adjusted so that its outer 

 lines cover the meridians at the points indicated. The lines of 

 the scale then subdivide the space between the meridians into 

 eight sections, each corresponding to 15'. The middle line of 

 the scale gives the position of the 86th meridian, the next 



Am. Jour. Sci.— Fourth Series, Vol. XIII, No. 11.— May, 1902. 

 24= 



