Note on the Perspective Drawing of Mt. Cook Locality.

In this drawing the perspective projection on the vertical plane was adopted, and, in order to represent a fairly extensive area, viz., from the Mount Cook Hermitage to the upper part of the Godley Glacier, the view was considered to be taken from an elevation of almost 8 miles, while the distance and bearing from the Hermitage equals 17 miles and 216 1/2deg. respectively.

The drawing was based on the one-inch-to-the-mile map and approximate contours were interpolated for every 1000 feet from the heights given on the map. A grid was then drawn on the map, thus providing, when the grid was thrown into perspective, a guide to drawing in the map information. When represented according to their perspective heights, the contours formed a good framework for the topographical features, the details of which were to a great extent filled in from photographic data obtained from various alpinists.

For the projected shadows, the sun's rays at an angle of 30deg. with the horizontal was chosen in the plane of the picture. The points page 51 of shadow were obtained by the aid of sections—the points lying in that part of the section which intercepted the solar rays—taken at fairly close intervals across the map, and the lines of shadow were obtained by interpolating the shadow points.

The chief consideration in the execution of the perspective drawing was a general degree of accuracy, and this appears to have been attained when alpinists, such as Messrs. A. P. Harper (President, N.Z. Alpine Club), W. A. Kennedy, and others, find no difficulty in recognising features independent of their names. It also gives at a glance a comprehensive view of the Mt. Cook region. In some important respects this is the first map of its kind produced in New Zealand.