46 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



Streaked with brown or black, another is rather light (oak) 

 brown ; and the remaining six definitely verge towards or are 

 light in colour, two being olive-brown, one light red, one light 

 brown, one (deodar cedar) light yellow-brown, and one (satin- 

 wood) cream or light yellow. In the last two classes, ^'■slightly 

 durable'' and '■^perishable,'' are included nine woods, all of which 

 (with one possible but not probable exception) are light coloured. 

 It will, therefore, be noted that among Indian timbers there is 

 an increase in the percentage of light-coloured timbers with a 

 decrease of durability, yet in detail the rule under discussion 

 breaks down (as it does on more detailed examination of the 

 woods of single Indian genera). 



The conclusion to be drawn is that colour is no safe guide 

 to the durability of wood, though the most perishable appear 

 generally to be light coloured ; for there are dark-coloured woods 

 by no means durable, and light-coloured woods of exceeding 

 durability. 



This subject is one on which many members of the Royal 

 Scottish Arboricultural Society could give and collect much 

 valuable and needed information. The statistics supplied might 

 be confined to cases in which the wood was exposed to air and 

 water (fences, posts, exposed woodwork of buildings, timber in 

 mines), and should include numerical details of the longevity of 

 particular objects. In this connection examples of rapid rotting 

 are quite as important as these of prolonged soundness. Very 

 important would be particulars of the geographical position and 

 exact situation and surroundings of the timber. It is in the hope 

 of inducing such co-operative collation of information that this 

 note is written. I shall be most grateful to any members who 

 will be so good as to procure for me particulars concerning the 

 durability of pit-props made of various woods, either untreated 

 or treated with preservative liquids. The information might be 

 sent to me at the Imperial College of Science and Technology, 

 South Kensington, London, S.W. 



