46 EXPERIMENT STATION RECORD. {Vol.38 



In the case of first tapping the renewal may be considered good if the renewed 

 cortex Is 85 per cent of the thickness of the untapped cortex within three years 

 of tapping. The renewed cortex of some old trees which had been severely 

 tapped had an almost uniform thickness of about 5 mm., or 50 per cent of the 

 thickness of untapped cortex. 



Hevea tapping results, Experiment Station, Peradeniya, 1916, T. Fetch 

 (Dept. Ayr. Ceylon Bui. 34 (1917), pp. 10). ~A progress report on tapping ex- 

 periments started in 1912 (E. S. R., 36, p. 243) and on some experiments 

 started in 1914-15. V tapping is being compared with simple oblique cuts, 

 tapping continuously on one quarter with tapping on the opposite quarter every 

 three raontlis, and tapping continuously on half of the circ umf erence with 

 tapping on the opposite side every three months. 



Increased yield of turpentine and rosin from double chipping, A. W. 

 ScHOEGER and R. L. Pettigkew {U. S. Dept. Agr. B^il. 561 {1911), pp. 9, pis. 2).— 

 This bulletin gives the results for one season of experiments under way at 

 Columbia, Miss., in which standard, narrow, and double chipping are being 

 compared. 



As a result of the first year's operation upon virgin timber double chipping 

 produced 31 per cent more turpentine and 36 per cent more rosin than stand- 

 ard chipping. The net gain from double chipping was about $450 per crop of 

 10,000 faces. The height of the face at the end of the season was approximately 

 the same as that of the standard face. Narrow chipping produced 17.5 per 

 cent less turpentine and rosin than standard chipping and the faces were only 

 h;vlf as hisli tis the standard faces at the end of the season. 



Developments in the marking of western white pine (Pinus monticola) in 

 northern Idaho, C. K. McHaeg, J. Kittredge, J. F. Preston, et al. (Jour. For- 

 estry, 15 {1911), No. 1, pp. 871-885). — This article describes the new marking 

 rules for the white pine type on the Cceur d'Alene Forest. The work of pre- 

 paring the rules was conducted under the direction of the Office of Silviculture 

 of the Forest Service of the U. S. Department of Agriculture during 1915-16. 



A practical xylometer, J. S. Illick {Jour. Forestry, 15 {1911), No. 1, pp. 

 859-863, figs. 2). — An xylometer used by the author during the past five years 

 in connection with various forest investigations is here described and illus- 

 trated. 



A simplified method of stem analysis, T. W. Dwight {Jour. Forestry, 15 

 {1911), No. 1, pp. 864-810). — ^The author here outlines a method of stem analysis 

 which, it is believed, will make possible a greater number of growth studies 

 so as to determine to some extent at least the factors controlling variation in 

 growth and the effect of those factors in various localities. 



What is a basis for yield tax? F. Roth {Jour. Forestry, 15 {1911), No. 7, 

 pp. 886-890). — The author here presents and discusses a basis for determining 

 the yield tax on wild woods. This provides for a universal yield tax of around 

 5 per cent on the assumption that the forest pay an equivalent of a property 

 tax of $8 per $1,000 on full assessment. 



The kiln drying of lumber, H. D. Tiemann {Philadelphia and London: J. B. 

 Lippincott Co., 1911, pp. XI+316, pis. 22, figs. 39).— A practical and theoretical 

 treatise, the successive chapters of which deal with the structure and prop- 

 erties of wood ; common practices in drying ; how wood dries, shrinkage, warp- 

 ing, and case-hardening; the principles of kiln drying; the circulation and the 

 method of piling; special problems in drying; the improved water spray humid- 

 ity regulated dry kiln; drying by superheated steam and at pressures other 

 than atmospheric ; theoretical considerations and calculations, humidity, 

 evaporation, density, tlie drying cycle, amount of air and heat required, ther- 



