152 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



and the volume, would probably be an accurate one, because 

 the selection of the stems, upon which the whole accuracy 

 of the method turns, would be corrected by the balancing 

 effect of the form-factor against the height and the volume. 

 Such a method has been evolved and is in use. 



There would seem to be limitations to the general usefulness 

 of the form-factor, and some other means of expressing more 

 accurately the degree of taper of trees might be desirable. 

 The form-height, which is the product of form-factor and 

 height, has been used, while some foreign experts, notably 

 in Sweden and Canada, prefer the use of the form-quotient, a 

 type of the True or Normal Form-factor, which appears to give 

 good practical results. In the meantime, it would seem that 

 the " Form "-factor israther inaptly named. 



N.B. — The figures accompanying this article are not drawn 

 to scale. This is impossible, owing to the great differences 

 in size of the trees depicted. 



20. Logging in North-West America (British Columbia 

 and Pacific States). 



{With Plates.) 

 By James Kay. 



The development of the various methods employed for handling 

 and transporting logs and timber in western North America has 

 been due to the necessity of reaching forest areas, the timber of 

 which could not be profitably extracted by means of drivable 

 streams, oxen or horses. Hence the necessity of logging rail- 

 roads, donkey engines, flumes (Plate VII., Fig. i), chutes, etc. 



Flumes are indispensable for the cheap and rapid transporta- 

 tion of timber from rough mountainous regions which would be 

 otherwise commercially unprofitable to log. They can be con- 

 structed more cheaply than a railroad, and can be operated 

 without fuel or skilled labour or mechanics, and without rolling 

 stock. 



The first step in flume construction is an accurate survey of 

 the proposed line of flume, so that a reliable profile map of the 



