37*2 Trial of Timber Jacks and a Monkey Winch. [July. 



Observations on the Use of Each Device. — Both types of 

 device were simple to operate and no difficulty was experienced 

 in the test at Sparsholt. It may, however, be observed that 

 before men can become skilled operators a certain amount of 

 continuous practice is necessary. The mechanical construction 

 of the machines is robust and simple and there appeared little 

 likelihood of any defect occurring in the working parts. Both 

 types of machines have been built to withstand excessive over- 

 loading. At no time was a very big load imposed on any of 

 the devices, as the timber was all shallow rooted, whereas the 

 timber in the test at Long Sutton was deep rooted. For this 

 reason and the fact that the average diameter of the timber was 

 smaller it is impossible to compare the results of the two tests. 

 For similar conditions to those obtaining at Sparsholt the jacks 

 can be regarded as very useful for land cleaning over a protracted 

 period. The same remark applies to the monkey winch, though 

 the usefulness of this device is greater than that of the jacks, 

 because of its high load extraction capacity and the facility 

 with which it can work in dense undergrowth. 





Jacks. 



Winch . 













Stools or 





Stools or 





Coppice. 



Trees. 



Coppice. 



Total number of stumps extracted ... 



9 



2 



27 



Diameter of stumps in inches — 









Smallest 



12 



9-5 



12 



Largest 



27 



10-3 



43 



Average 



18-5 



9-9 



23-3 



Number of working hours ... 



1 hr'26 m. 



1 hr. 1 m. 



2 hr. 37 m 



Average time per stump in minJ — 









Grubbing 



4-4 



22-3 



22 



Extraction 



5-2 



8/3 



3-6 



Total 



9-6 



30-5 



5-8 



Average cost per stump 



4-0d. 



12-8d. 



3-6d. 



Cost per sq. ft. of cross section 



l-7d. 



23-9d. 



lid. 



Cost per cubic ft. of timber lifted ... 



1-Ori. 



10-5d. 



•6d. 



Average volume of crater in cu. ft. 



4-3 



2-1 



8-5 



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