370 Trial of Timber Jacks and a Monkey Winch. [July, 



7. Mechanical construction having regard to simplicity and 



access to wearing parts. 



8. Method of extraction having regard to simplicity and 



safety. 



9. Ease of handling, including manoeuvring to the scene of 



operation. 



10. Usefulness of the appliance for other work. 

 Description and Test. 



Sale Price : March, 1922. 



£ s. d. 



A. Ten-ton jack 13 10 



Five-ton jack 8 15 



B. Monkey winch (with stumping 



tackle) 57 



Monkey winch (without stumping 



tackle) 47 10 



The Timber Jack. — The jack is of the well-known rack and 

 bar type, the distinguishing feature being that the casing is 

 made to move up and down the pillar instead of remaining 

 stationary. This casing carries two lifting claws fitted at different 

 heights, and on opposite sides, the top claw being at a con- 

 venient height to go under a load which the bottom claw has 

 raised to its limit. To transfer the weight from the bottom to 

 the top claw simply involves turning the pillar round. 



The pillar of the jack consists of hard railway steel of great 

 strength. Each jack is fitted with two spears of different lengths 

 supported by guides, and by these the working range of the 

 jack is considerably increased. 



A simple device on the side of the casing releases the pawl 

 action and thus permits the jack to be raised or lowered right 

 up or down without working the handle .. 



To uproot a stump, a trench is dug on one side and the 

 jack placed under a strong root. To prevent the base of the 

 jack from sinking too far into the ground a steel base or a stout 

 plank is placed underneath. Upon the lever being worked the 

 jack rises and tears the stump bodily out of the ground. 



Method of Trial. — Two men only worked on these machines 

 and were equipped with grub axes, a spade and a crowbar. The 

 jacks first worked approximately 1J hours upon elder, hazel and 

 maple and shallow-rooted stools. Considerable hand grubbing 

 was done. It was observed that upon a stool being raised to 

 a certain limit, the roots holding the stool to the ground were 



