PREFACE. 



A NEW edition of this volume having become necessary, 

 I have made various changes, so as to render some of the 

 mathematical problems more easily understood. I have also 

 simplified and shortened some of the calculations. 



The appendices have been considerably altered. Some of 

 those contained in the former edition have been shortened, 

 while I have added a set of complete yield tables for oak, 

 beech, Scotch pine, spruce and silver fir, and preliminary 

 tables for several other species. The former are the result 

 of many years' labour on the part of the German Association 

 for the collection of forest statistics. They give the progress 

 of development of the several species in Germany, more 

 particularly in the northern part of it. The data contained 

 in yield tables enable the forester to determine the quantity 

 of timber and firewood produced on lands of varying yield 

 capacity under the supposition, that the progress of the woods 

 has not suffered from any extraneous interference. Hence, 

 they serve to determine the yield, which may be expected, and 

 to gauge the financial results of the industry, if the land is 

 planted with one or the other species. I have satisfied myself, 

 that the tables apply, in a general way, to the conditions found 

 in the South of England, and also in the Midland Counties. 



It has been suggested, elsewhere, that such tables should be 

 altogether rejected, because the statistics, upon which they 

 are based, were collected on the Continent, but I cannot accept 

 such a view. To construct tables, based upon data collected 

 in this country, will take many years, and, surely, it is more 

 sensible to use the tables now given than none at all. In 

 the latter case, we should continue to grope in the ^i^CO^'^ 



