(1) Experiments conducted by the U. S. Division of Forestry (Dr. B. E. Fernow, Chief), under the direction of Professor J. B. Johnson. About forty thousand tests were made, distributed over thirty-one American species, the results, so far as obtained, being undoubtedly the most valuable in existence. The detail considered and methods evolved have in a way reclassed the testing of woods and must influence all future efforts, but results are disappointing in that they have been obtained for so few species, and some of these of commercially secondary importance. These experiments are characterized as follows: Completeness and Reliability of Records. Large and Small Test Pieces. Moisture Conditions Standardized at 12% Dry Weight. Samples from Representative Portions of Tree. Selection of Representative Trees. Uniformity of Methods. Large Number of Individual and Total Tests. Small Number of Species Covered. Specific Gravity Determinations. Soil and Forest Conditions Indicated. Botanical Accuracy Assured. These experiments are originally described in Circular No. 15 and other publications of the U. S. Forestry Division, also in "Materials of Construction," by Professor J. B. Johnson. (2) Experiments conducted for the Tenth U. S. Census by Mr. J. P. Sharpless at the Watertown (Mass.) Arsenal upon specimens botanically selected by Professor Sargent. These experiments are less complete in detail, and averages are based upon infinitely [p005] fewer tests for each species. So far as known most specimens were from butts. Nothing is known of moisture conditions save that specimens were "carefully seasoned." Tests were upon about twelve hundred specimens divided over four hundred and twelve species, allowing but a small number for each. The series is most valuable in that the species attempted were so numerous as to present an almost complete American series; in that the botanical identity of the specimens was beyond question, and because it gives a general idea of relative values. The results are frequently quoted and appear on the accompanying pages in spaces immediately following those occupied by, or set apart for, "Forestry" figures or their alternates. The tests are characterized as follows: Botanical Accuracy Assured. Specific Gravity Determinations. Uniformity of Methods. Limited Number of Individuals and Total Tests. Large Number of Species Covered. Small Test Pieces Only. Selection and Moisture Conditions Indefinite. They are originally described in Vol. IX, Tenth U. S. Census; Executive Document No. 5, Forty-eighth Congress, First Session; in Catalogue of the "Jesup Collection," by Professor C. S. Sargent, and elsewhere.