RECENT INVESTIGATIONS IN REGARD TO QUALITY OF TIMBER. 289 
metres). The two species also agree in regard to the lightest 
timber being produced by young trees, the maximum being 
reached about the 60th year. 
Where complete sections were examined, the sp. gr. was found 
to increase from the centre outwards (°333 within the 31st ring, 
*382 between the 60th and 91st rings). This shows that the 
increase in sp. gr. in wood formed after, say, the 60th year is 
more than sufficient to counterbalance the increase in sp. gr. due 
to the formation of duramen. 
In regard to variations in shrinkage, the timber of Weymouth 
pine agrees in general with the foregoing species, thus :— 
Shrinkage at 1 metre= 8:8 7. 
Me Weed eg ee 
Shrinkage of the inner 30 rings= 7:9 7. 
< Tie eebCr Es og a LE 7, 
lI 
The average shrinkage is put at 9°1 %, which is considerably 
less than that of the other conifers examined, and makes Wey- 
mouth pine specially suitable for certain purposes. 
Resistance to pressure was greater in the lowest section than 
in any other. 
The limits of variation in sp. gr. were found to be :— 
(a) For definite periods of growth, . ‘467 and ‘322. 
(6) For whole sections, . ‘423 and 327. 
The average for the whole of the timber of mature trees is 
placed at °370. 
The limits of resistance to pressure in lbs, per square inch of 
section were 7746 and 4457, the average being 5960, 
V. With tHe BreEcu. 
Here, also, the heaviest wood was found near the base of the 
tree, a more or less gradual reduction in sp. gr. taking place as 
the stem was followed up to the crown. 
When complete sections were examined, it was found that 
the sp. gr. decreased from the centre outwards, Thus, on the 
average, 34 trees showed that the wood comprised by the Ist to 
the 30th rings had a sp. gr. of 705, that comprised by the 61st 
to the 90th rings a sp. gr. of ‘663, while the sp. gr. of the wood 
of the 121st to the 150th rings was °632. 
