142 



Trees, Stars, and Birds 



' N. Y. State Conservation Commission 

 FIG. 92. Tree surgery. 



N. Y. State Conservation Commission 

 FIG. 93. The surgeon at work. 



in trees with a mixture of two parts of sand and one 

 part of Portland cement. For large cavities, broken 

 stone and brick are used besides the sand and cement. 

 In place of these materials a mixture of sawdust and 

 asphaltum is now recommended. It is not so rigid as 

 the cement. For cavities in swaying branches three or 

 four times as much sawdust as asphaltum is used ; for 

 cavities in trunks the mixture is made in the proportion 

 of five or six parts sawdust and one part asphaltum. 

 The filling is not brought up flush with the outside of the 



