132 



A. ASHE ON TWO-SPEED FIXE ADJUSTMENTS. 



the examination of unprepared commercial products, where a large 

 amount of material has to be gone over lest minute quantities of 

 foreign ingredients, irregularly distributed throughout its mass, 

 escape detection. 



It becomes evident, therefore, that it is desirable for some 

 workers to have a fine adjustment which, whilst on the one hand 

 possessing the slowest and smoothest movement possible, is yet cap- 

 able of giving a far more rapid motion when needed ; and it should 

 do this without requiring the removal of the hand from the milled 

 head, or the performing of any operation whatever to bring the 



B 



D 



Fig. 1. 



other speed into action, because any distraction of the mind 

 caused by having to change the speeds will greatly reduce the 

 utiUty of the adjustment. 



Some years ago I designed an apparatus to fulfil the above 

 requirements, and I intended to construct a model and show it to 

 the members of the Club, but the want of accurate metal- 

 working tools prevented this being done. The matter therefore 

 remained in abeyance until our Editor — ever on the alert for 

 anything which may interest the members — seeing my plans, 

 persuaded me to take the matter up again. 



The two-speed fine adjustment screw which I first designed is 

 shown in the accompanying diagram (Fig, 1). It will be seen 



