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10 Dr. Mac Culloch ow Mineralogical Hammers. 



I may add, lastly, that when worn by use, the hammers of this 

 construction are more easily repaired than the common ones ; 

 as, by grinding one face to a small distance downwards, four 

 edges are at once replaced. 



In concluding this paper, it will not be improper to suggest 

 that the same principle might be advantageously extended to 

 the ordinary hammers of quarrymen and masons, and more par- 

 ticularly to those of road-makers. The forms of these latter are 

 almost in every instance very faulty, and the consequences are 

 important, as they add double or treble the expense to that 

 which is, in many places, one of the most costly parts of road- 

 making. It is not only indeed in the shape, but in the use 

 of the hammer, that the system of breaking stones for roads is 

 defective. Independently of the fatigue of standing, the same 

 velocity, or impulse, cannot be communicated by two hands 

 as by one, from the crossing, or obliquity of the arms ; and, 

 with a single-handed hammer, sitting, one person can easily do 

 the work of two standing, possibly more. This practice has 

 indeed been partially introduced of late, but the prejudices 

 against it are still very general. To render it perfect, the forms of 

 the hammers should also be improved according to the principles 

 already laid down ; and the labourer should further be provided 

 with a set of these, of different weights, using them in succession 

 as the size of the materials diminishes under his hands. 







