July, 1912.] 



37 



TIMBERS. 



FELLING TREES AND BLOWING 

 STUMPS WITH DYNAMITE. 



Blowing Stumps with Dynamite.— 

 Kentucky A gricultural Experiment Sta- 

 tion of the State University : Bull- No. 

 154, pp. 19-31. Lexington Ky„ 1911. 



A. T. Anderson. Recent Developments 

 in Explosives.— The Engineering 

 and Mining Journal, Vol, 93, No. 

 5, pp. 270-273. New York,February 

 3, 1912. 



J. T. Garrett. Dynamite for prepar. 

 ing Land. — Experiment Station Re- 

 cord. Vol. XXV, No. 9, p. 890. 

 i Washington January 10, 1912. 



(Bulletin of the Bureau of Agricultural 

 Intelligence and of Plant- Diseases, 

 3rd Year-Number 4, April, 1912.) 



In the felling of trees or the removal 

 of tree stumps a great deal of labour can 

 be saved by the use of various explosives 

 and especially of dynamite. 



Tree felling. — Trees may be felled, 

 either by girdling them with an outer 

 charge or by causing an explosion in 

 their centre. 



In the first case a hollow cord filled 

 with dynamite is placed round the tree 

 and kept in position by nails, or other 

 means, and is fired by a fuse and cap ; 

 tree is felled by a charge C. of dynamite 

 given by the following formula. 



G = 0-00069 x a « (1) 

 where C represents the weight in pounds 

 and a the diameter of the tree in inches. 



In the second case a horizontal hole in 

 the trunk is made with an augur ; in it a 

 dynamite cartridge furnished with fuse 

 and cap is placed and then carefully 

 tamped. The charge C. of dynamite is 

 given by the following formula : 

 C. * 0-000103 as (2) 



in which C. and a represent pounds and 

 inches respectively as in formula (1). 



Blowing of Stumps.— The hole is bored 

 with a good augur at an angle of about 45 

 degrees, so that the charge will come 

 under the center of the stump. The 

 diameter of the hole is 1*6 to 2 inches. 

 The charge is placed at the bottom of 

 the hole, the primer put in, and carefully 

 tamped. 



If the stumps are partially decayed, of 

 course the charge will have to be located 

 under some firm part of the stump. 



In blowing very large stumps, the 

 whole charge should not be placed in 

 one hole, but several holes may be bored 

 from different sides and made to intersect 

 under the centre of the stump. The 

 primer is placed at the intersection of 

 the holes and the other cartridges put 

 in so as to touch the primer. 



Only one part of the charge necpssary 

 to remove a large stump may be used at 

 first to split it. After the stump is split 

 the parts may be blown as separate 

 stumps. 



The amount of dynamite to be used 

 depends on the diameter of the stump ; 

 the nature of the root system ; whether 

 the stump is green or partly decayed, 

 and the character of the soil. 



In Kentucky; two different lots of 

 stumps were blown by the Experiment 

 Station in the spring of 1911. One lot 

 consisted of 102 stumps, mostly of dead 

 oak, The other lot comprised 16 stumps 

 9 of which were green (3 hackberries, 1 

 elm, 1 Cherry, 1 maple and 3 oak). 



The following are the figures concern- 

 ing the first lot. 

 Average diameter of stumps 16 inches 

 Total weight of dynamite 

 required ... ... 132 lb. 



Time required for one man 51 hours 

 Cost of dynamite ... $ 22 85 



Caps and fuse ... ... $ 235 



