248 



FELLING AND CONVERSION OF TIMBER. 



ii. J Has/in f/ 



by Gunpowder. 



The stump which is to be blasted by a charge of gunpowder 

 is bored best from its flat surface by means of a large auger 

 (Fig. 153), so that the bore-hole may go down to the junction 



of the roots. In case the tree 

 is rotten at the heart, the boring 

 must be made from one of the 

 sides. The charge should con- 

 sist of 1J, 3 or 4J ozs. of blast- 

 ing-powder, and a fuse should 

 be introduced, or some other 

 arrangement made for firing 

 the blast. Frivolin and Kyssel 

 used ordinary percussion caps 

 for the purpose. Fig. 154 shows 

 a simple detonator, the ring (a) 

 being for the insertion of a 

 handle for screwing it into the 

 bore-hole, whilst (5) is a simple 

 trigger for striking the cap. 

 Urich improved matters further 

 by using an apparatus with a 

 needle for firing the cap, which 

 was placed on the top of the powder, as shown in Figs. 155, 

 156, the former giving its external form, and the latter a 

 section through its axis. The apparatus has a bore sufficient 



Fig. 15B. Augers for boring wood. 



Fig. 151. Frivolin's detonator. 



for the working of the needle (m o). It is closed by a 

 screw-lid (/>) in which the cap (n) is placed. In order 

 to prepare the apparatus for firing, the needle is raised 

 by means of the ring (m), and a steel pin is placed in the 

 aperture (d). The lid (/>) is then removed, and screwed 



