HOW GUN-BARRELS ARE MADE. 221 



all invariably veneered or plated with ribbons of this 

 ornamental iron. I shall now dismiss this subject ; 

 after remarking, that certainly a very handsome barrel 

 may be made after this principle, if too much twisting 

 be avoided. It has been seen that the rods are twisted 

 until there are fourteen turns in the inch of length : 

 an excess productive of the detrimental effect men- 

 tioned ; while, had there been but two turns, a large 

 proportion of strength, if not all, would have been re- 

 tained. One turn only, under the same circumstances, 

 would very likely be highly beneficial ; indeed I 

 have found it to be so : one twist binds the interior 

 strands, as the outer does the interior in a rope, and 

 thus adds strength. This shows that there is a medi- 

 um in all things." 



HORSE-SHOE NAILS. 



" The use of old horse-shoe nails is of a date nearly 

 coeval with the use of small fire-arms. These nails 

 are made from rod iron of the best description ; and 

 the hammering cold, or tempering the nail, so benefits 

 and condenses the iron as to improve it greatly. The 

 method in use until a late period was to fill and force 

 into an iron hoop, of six or seven inches diameter, as 

 many stubs as it would contain, to weld the whole, 

 and draw them down to a bar of such dimensions as 

 might be required. Modern improvement, however, 

 has shown the advantage of cleansing the stubs per- 

 fectly by a revolving drum, and then fusing and 

 gathering them into a bloom on the bed of an air 



