C.—3.

Section F.—Utilization Plants. 58. The major activity during the year has been the completion of the demonstration log gang sawmill, now known as the Waipa State Mill, on the Whakarewarewa State Forest about three miles from Kotorua. As a demonstration unit the mill has been thrown open to inspection both by sawmillers and forestowners in order that all may benefit by the Department's experience in adaptation and integration of North European and North American equipment to the utilization of New Zealand-grown exotic pines. This experience has been largely confirmatory of the Department's'original conception of the enterprise, but also invaluable in indicating future modifications and developments. Refinements in operation, of course, are still being developed as a result of accumulating experience. First and foremost is the experience gained in logging insignis pine oft pumice country. Due to lack of silvicultural treatment at appropriate times, the stands contain such an excess of standing dead and dying timber that not only have they been dangerous to log, but also expensive. Neither is it impossible that this condition of the forest may so favour the development of the destructive insect Hylastes ater as to not merely destroy all natural regeneration but to prevent planting for several years, and then only at a high cost. Although tractor arch logging was originally provided for, tractor skidding has been employed as a trial, but with limited success, even soaking in the log pond and log-washing at the log-conveyor failing to remove the excessive quantities of pumice picked up by the logs when ground skidded. Both local and imported arch equipment is now being brought into operation, with a marked reduction in the average amount of pumice picked up by logs. The step up in production as a war measure to 125 per cent, of planned capacity naturally prevented the building up of log reserves to an adequate level, with the result that top logs were insufficiently seasoned and have given trouble as sinkers when placed for sorting purposes in the log pond. With a diesel-engined hauler supplementing the existing tractor equipment, adequate reserves and seasoning will be possible and sinkers eliminated. Owing to the proven economy of longlength log handling and haulage in clear-felling activities, the log pond is being supplemented by mechanical log-crosscutting equipment and dry-sorting facilities. Longer soaking and improved log-washing, together with other developments, are expected to reduce pumice troubles to an acceptable standard in respect both to the amount deposited in the log pond, which must be sluiced out from time to time, and to that reaching and dulling the saws, with consequential reductions in output. in the sawing of reasonably-straight even tapered logs the North European log gangs and edgers, &c, have functioned almost perfectly. The capacity is well illustrated by the fact that as many as 922 8-in.-mean-diameter logs have been sawn in seven hours fifty-five minutes. By no other means could such economy of sawing be achieved. It is already clear, however, that even the closer-planted stands are yielding an appreciable percentage of logs which are so rough as to necessitate working up on band-saws. Particularly in the future milling of 8 ft. planted stands, provision will require to be made for the incorporation of such units. In addition, a fundamental study is warranted into the possibilities of log gang saw adaptation to the sawing of short billets, an enormous quantity of which is now wasted in logging and contributes to the danger of widespread development of Hylastes ater. Although a high standard of sawing technique has already been developed, it was not attained without searching investigation and trial by the operating staff. The elimination of waviness in sawing in the main frame and the improved results following this substitution of spring set by swaged saws reflect credit on the responsible officers and staff. The engineering features of the remainder of the plant being largely orthodox, deserve no special mention. Fuel-bin capacity was found inadequate for week-end operation of the kilns, and additional bins are being provided accordingly. In the box-factory operatives are being trained in the use of the new equipment, and full production will be attained for the next boxmaking season. Fire-protection services are carefully maintained and regularly tested. Minor engineering work of a maintenance character was carried out in connection with the creosote plants at Waipa, Hanmer Springs, and Conical Hill, the operations of which are referred to elsewhere. At Waipa the supply of steam from the main State mill power-house has greatly facilitated operations.

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