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the supply of the common indigenous softwoods can be met by the use of other timbers for most parts of buildings, but to do so it is necessary to overcome deep-rooted prejudices. As the background to recommended changes, it is pointed out:— (a) That there are a number of timbers with adequate strength for building provided that they are graded correctly —exotic pines, larch, Douglas fir, and kahikatea. (b) That the extending facilities for wood-preservation provide the means for giving durability to the non-durable species. (c) That sap-stain in the light-coloured timbers can be largely avoided by the use of chemical dips or kiln drying at the production source. (d) That non-heart grades of the several beech species are certainly as durable as non-heart rimu, and that the heart grades of red and hard beech are stronger and more durable than equivalent grades of heart rimu. (e) That immunization of tawa and other Zycto-susceptible hardwoods is to be carried out in plants now being erected to improve their utility for interior woodwork, furniture, and flooring. (/) That the production of good grade structural sizes, 5 in. or more in width, from exotic pines is practicable. The disadvantages of large knots, pith, and warping tendency in the smaller scantling sizes become less significant in the larger sizes as the ratio of knot size to face width decreases. 45. More specifically, it may be noted that treated tawa and treated (or heart) silver and red beech provide high-class flooring, and that " flooring grade " exotic softwoods are suitable after preservation for covered or light-wear floor. Weatherboarding from treated kahikatea and exotic softwoods in the appropriate grades is being used more widely. For sub-floor work the supplementary timbers include treated exotic softwoods, heart larch, and Douglas fir, and heart red beech. It is a much more difficult matter to supplement the supply of exterior joinery timbers for which heart totara, redwood, and western red cedar have set a high standard ; the treated sap-wood ■of kahikatea, totara, and of insignis pine from clear timber between knot whorls is potentially-important material, provided that paint-coats are well maintained. Another problem in building is the difficulty in meeting the requirements for long-length timbers of high grade used in pitched roofs ; this applies to the normal scantling sizes but not to the wider sizes used in light-truss construction employing insignis pine. It may also be remarked that the deep joists and sarking in flat-roof construction are uses for insignis pine in which grade requirements are easily fulfilled. 46. Grading of Timber.—The largest study undertaken during the year was of .a fundamental nature and involved the examination of 16,000 board feet of insignispine boards at the Waipa Mill. An average run of logs in each of the 10 in., 12 in., 14 in., and 16 in., small-end-diameter classes was gang sawn. The nature, size, and position of all defects in each face of every board was drawn on sheets specially prepared for ihis purpose. This method of recording defects was adopted only after photographic methods had been found unsatisfactory. Analysis of the defects recorded in this study is necessarily slow. The board grades considered in this study include " finishing " and " dressing" grades as defined in the New Zealand Standard Specification No. 169, .another grade intended for factory use, and several variations of those grades. It may be remarked at this juncture that " finishing grade " (as specified) admits a maximum of 5 per cent, and " dressing grade " (as specified) a maximum of 26 per cent, of the total sawn product of the two diameter classes analysed to date. Among the conclusions drawn from inspections of painted and creosoted weatherboarding of insignis pine on occupied houses is the need to exclude large knots extending to the arris on the face.

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