The Sand Blast. 641 



ance of tlie face, caused, perhaps, sometimes by the inequal- 

 ity of the texture of the marble, and sometimes by the vari- 

 ations in the movement of the blast across the surface ; for 

 if the blast stands but a fraction of a minute on any part 

 of the slab, a deep hole will be cut proportionate to the 

 time it is stationary. A very few mmutes will drill out 

 two inches or more. 



Without the utilization which Mr. Bridges effected of 

 this simple yet wonderful invention, the enormous contract 

 of completing and setting up in all parts of the country 

 these headstones, would have been almost impossible. At 

 all events, the work would have required long time, and 

 cost the Government hundreds of thousands of dollars more 

 than is awarded for this work. 



The applications of the sand blast are multiplying almost 

 daily. The etching of dainty designs on windows, the rich 

 ornamentation of goblets, vases, etc., the delicate frosting 

 on silver, are among its uses, while channelling and groov- 

 ing in quarries may yet be accomplished by it. 



This nineteenth century is wonderful in its record of bril- 

 liant inventions and startling discoveries. In its dawn it 

 looked upon the steamboat and the railroad, and scarcely 

 had it recovered from these gigantic strides in the march 

 of improvement, before the lightning was harnessed to its 

 triumphal car of progress, and made to flash human thought 

 from continent to continent, over land and sea. Tlie little 

 prism that had been a mere scientific toy to separate the 

 beautiful colors of the rainbow, has become a great ana- 

 lyzer of chemical compounds themselves, and across whose 

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