THE SAND-BLAST. 



3^1 



rocky strata were soft and yielding, and were the more readily cut 

 away; but where the opposing surface was hard, as in the case of tlie 

 black cap-pieces, the action was less rapid, and the reduction of the 

 rock less decided. Glancing off from these, the whole force of the 

 driving sand was projected against the strata immediately below, 

 thus reducing it in size till there seems hardly circumference enough 

 left to sustain the weight above. 



Fig. 1. Sand-cut Colttmns in Monument Pake. 



So much for the observations of the geologist and explorer, maJe 

 nearly half a century ago, and placed on record as forming but one of 

 the many startling features of that Avonderful region, but suggesting 

 to the traveler little else than a reasonable theory by which to account 

 for a hitherto mystei'ious class of physical phenomena. From this, 

 the record of the student of Nature, we turn to a second record, more 

 ]n*actical in character, and having a direct bearing u^ion the subject 

 under review. 



Whether the author or inventor ot the modern sand-blast deserves 

 any less credit for having had his idea anticipated in the workshops 



