radial direction of any two whorls ( W ). We have then merely to apply the formula
which we may simply write r =ã₤eÿ£¢ö¡ã₤cotã₤öÝã₤, etc.; since our first radius or whorl is regarded, for the purpose of comparison, as being equal to unity.
Thus, in the diagram, OCã₤ãã₤OEã₤, or EFã₤ãã₤BDã₤, or DCã₤ãã₤EFã₤, being in each case radii, or diameters, at right angles to one another, are all equal to eÿ£¢(üã₤ãã₤2)ã₤cotã₤öÝã₤. While in like manner, EOã₤ãã₤OFã₤, EGã₤ãã₤FHã₤, or GOã₤ãã₤HOã₤, all equal eÿ£¢üã₤cotã₤öÝã₤; and BCã₤ãã₤BAã₤, or COã₤ãã₤OB =ã₤eÿ£¢2üã₤cotã₤öÝã₤.
As soon, then, as we have prepared tables for these values, the determination of the constant angle öÝ in a particular shell becomes a very simple matter.
A complete table would be cumbrous, and it will be sufficient to deal with the simple case of the ratio between the