The reception accorded this book since it was first issued in 1909, particularly the appreciation expressed by numerous woodsmen, has been gratifying. Letters of commendation have been received from users in all parts of the country. It is significant that the first typographical error discovered (a wrong figure in a logarithmic table) was pointed out by a ranger on'the largest tract of unsurveyed timber land in the United States, in Idaho. The second correction Was sent in by a Canadian cruiser. The incidents just mentioned illustrate the wide distribution of the volume and explain the present extension of it. As originally written, the book did not aim at circulation west of the Lake states; but from the first a large part'of the demand for it came from Westerners, chie?y those employed in the United States Forest Service. Revisions have been guided largely by this fact, and that is true especially of the present and first considerable revision, for aside from bringing the work up to date as concerns appliances and methods which have come into use since the first edition was written, the new matter and tables which have been introduced are mainly intended for the benefit of western woodsmen. As a result, material additions have been made under the heads Topographic Maps and Timber Estimating. The book, however, is not materially increased bulk, nor has there been any change in its chief pur pose, which is to serve the men who are carrying the load of actual timber work in this country. To these men, in whatever section they are, and whatever may have been their training, the author extends greeting.