Method to ascertain the Value of Growing Timber Trees, 327 



which the sulphuric acid can have an action, act different- 

 ly when there is an accession of atmospheric air. I have 

 remarked in another Memoir, that it is not the coal which 

 contains most pyrites, which gives in the inside of the 

 mines the inflammable gas known by the name of fire- 

 damp, but rather the coal which contains little or none 

 visible to the naked eye, and in which the sulphuret of iron 

 probably exists in particles not discernible. 



LVIir. Method of ascertaining the Value of Growing Timber 

 Trees, at different and distant Periods of Time. By Mr, 

 Charles Waistell, of High Holborn*. 



n SIR > 



V^onceiving that the Tables contained in the annexed 

 papers will afford useful information to growers of timber, 

 and tend to encourage the growth of it in these kingdoms, 

 and thereby promote the views of the Society of Arts, &c. 

 I trust you wilfhave the goodness to lay them before the 

 Society, as I have formed them with great attention. 



Having last autumn viewed some plantations made under 

 my direction about thirty years ago, I found the value of one 

 of them much to exceed my expectation. I became there- 

 fore desirous to devise some means of estimating what its 

 value might probably be at different future periods. I was 

 thus led to construct the first of these tables, and on the 

 completion of this, other tables seemed necessary; and T was 

 thus progressively led on to the construction of the whole. 

 For this purpose I searched in various authors for the mea- 

 sure of trees, in girt and height, at different ages, and ob- 

 tained similar information among my acquaintance. Hence 

 I collected, thai the increase in the circumference of trees 

 is generally from about one to two inches annually, and 

 from twelve to eighteen inches the annual increase in height. 

 Some fall a little short, and some exceed those measures. 



* From Transactions of the Society for the Encouragement of Arts, Manufac- 

 tures, and Commerce, for 1808. The gold medal of the Society was voted 



to Mr. Waistell for this communication. 



. X4 I shall 



