472 Proceedings. 



so as to be able to open the last valve in opposition to the pressure of the 

 atmospheric air, the emergent air was so hot as to be unbearable to the hand. If 

 the heated air, without having lost caloric, be allowed to expand to its former 

 dimensions it exhibits its former temperature ; that is, it cools by sudden 

 expansion. And this is so well known that it has been proposed to supply 

 apartments in hot climates with cool air, by compressing air in a close vessel, 

 allowing the increased heat to escape by contact of the vessel with the external 

 air or neighbouring substances, and then permitting the condensed air (at the 

 atmospheric temperature) to expand into the apartments, when it would have 

 a much lower temperature." 



You see at once that the condition of the air in the tubes of the atmos- 

 pheric railway bears the closest relationship to what takes place in the transit 

 of the air from the West to the East Coast. First, the rarefaction of air in 

 the tubes ; — this represents the expansion of air in its ascent to the mountain 

 ranges. The subsequent compression of air, for raising the escape valve is 

 analogous to the descent of the column of air from the ranges ; — and the escape 

 of the hot air at the valvular opening is a counterpart of the heated air 

 sweeping over the Canterbury plains. 



A paper on the Preservation and Treatment of the Timber of New 

 Zealand, by Mr. Buchanan, of the Geological Survey Department, is deserving 

 of some notice. 



The forests of New Zealand are cut down recklessly at all seasons of the 

 year ; and when the trees are sawn into square timber or planks no attempt is 

 made to preserve them against decay or deterioration. 



Greater attention should be paid to seasoning. I am doubtful whether we 

 do not, however, attach too great importance to the time of the year in which 

 the trees are felled. If cut down in summer they should be allowed to lie 

 where they are felled, and no branches cut off, so that the sap may be dried 

 off by evaporation from the surface of the leaves. Unless this be attended to, 

 the timber from trees cut down in summer, and immediately sawn up, will be 

 much deteriorated in value — the planks will warp and the lai'ger timber will 

 split and spoil fi-om hasty drying. 



On the whole, it is safer that the trees should be cut down, or killed by 

 "ringing," during the winter months. As soon as possible after being felled 

 they should be cut into square timber and planks, and these stacked in a 

 proper manner, and carefully protected from the sun's rays. 



Timber so cut, seasoned, and protected, might be branded as a guarantee 

 to purchasers. The letter of the brand would show the year in which the 

 timber was felled, just as silver plate is lettered to show the year in which it 

 was stamped. 



With respect to ringing trees which exude large quantities of gum from 



