162 Practical Forestry 



stout struts placed within the cavity at various of the 

 weaker points will go far towards preserving many an aged 

 specimen. When the cavity in a hollow stem is so large 

 that a person can enter it, the work of either filling with a 

 suitable composition or supporting with wooden struts is 

 greatly simplified. 



Recent experiments have proved the value of a mixture 

 of sawdust and asphalt for filling cavities. It is particu- 

 larly valuable in cases where concrete is too rigid and 

 unyielding, such as in dealing with trunks and branches 

 that are apt to be swayed about in stormy weather. The 

 materials are dry sawdust, that of Oak, Chestnut and 

 Beech being preferable, arid solid asphalt derived from the 

 refining of petroleum, which is at present in use for filling 

 the interstices of street pavements in various parts of the 

 metropolis. 



For filling cavities in heavy, swaying branches, one part 

 of asphalt to four of clean, dry sawdust will form a mix- 

 ture that is non-rigid and yields with the motion of the 

 branch in which it is inserted. In dealing with the trunk, 

 which is more rigid and less affected in stormy weather, a 

 larger quantity of sawdust should be used. The filling is 

 made by stirring dry sawdust into boiling asphalt until 

 the desired consistency is reached, and before the composi- 

 tion has cooled, it should be inserted in the previously 

 prepared cavity. As in cement filling, the preparation of 

 cavities to be filled with sawdust and asphalt should be 

 carefully attended to, the decayed wood and all soft and 

 rotten material being removed, and the interior surface 

 rendered sterile by an application of carbolineum or kero- 

 sene. For wound dressings, gas tar and liquid asphalt 

 is to be recommended, this combination forming a more 

 continuous and elastic covering than is the case when tar or 

 paint alone is used. 



Where the cavity is small and, as is often the case, filled 

 with water and decayed and decaying vegetable matter, 

 the following course is recommended : When only a few 

 inches deep, the water can usually be got rid of by mopping 

 it out with a sponge attached to a convenient handle, but 



