When, in 1882,I began my dictionary of tracks (see "Life Histories of Northern Animals"), I found that there was no literature on the subject. All facts had to be gathered directly from Nature. My first attempts at recording tracks were made with pencil and paper. Next, realizing how completely the pencil sketch is limited by one's own knowledge, I tried photography; but it invariably happens that not one track in ten thousand is fit for photographing, and it cannot be taken except when the sun is about thirty degrees above the horizon - that is, high enough to make a picture, and low enough to cast a shadow of every detail. Thus photography was possible only for about an hour in the early morning and an hour in the late afternoon. But the opportunity in the meanwhile usually was gone. I then tried making a plaster cast of the tracks in the mud. Only one such in a million was castable. As a matter of fact, none of the finest were in the mud; and the much more interesting dust-tracks were never within reach of this method. For most practical purposes I have been forced to make my records by drawing the tracks.