376 Pev field — Use of the Stereographic Projection, etc. 



which are frequently needed. It has not seemed that the tables in them- 

 selves are of sufficient interest to warrant their being printed as part of a 

 journal article, but the material will be printed if there is any demand for it. 

 For convenient use the figures are arranged as in logarithm tables. The unit 

 of measure adopted is 100, and the tables give the real values and the cor- 

 responding logarithm for every degree. By means of the tables data for 

 making a stereographic map of any desired size may be obtained with the 

 greatest ease. 



If there are those who wish to work out for themselves some of the prob- 

 lems of geography or navigation by means of the stereographic projection, 

 so as to test its possibilities, there are now available the engine divided pro- 

 tractors and plates described in the writer's previous communication, and 

 photo-engravings of the hemispheres, corresponding to figures 4, 8 and 9 of 

 the present article, could be made, reduced to 14 cm diameter to correspond 

 with the protractors. If stereographic maps meet with sufficient favor to 

 warrant their adoption, it will necessarily be some time before they and the 

 accompanying protractors can be engraved and printed. Their possibilities 

 are all that could be desired ; their adoption is a matter which geographers 

 and teachers must determine. 



Sheffield Scientific School of 



Yale University, New Haven, February, 1902. 



