problem. The pattern of the Sommeiller drill was 

 generally followed; that is, the drill was designed as 

 a separate, relatively light mechanical element, 

 adapted for transportation by several miners, and 

 attachable to a movable frame or carriage during 

 operation. Air was of course the presumed power. 

 To be effective, it was necessary that a drill auto- 

 matically feed the drill rod as the hole deepened, and 

 also rotate the rod automatically to maintain a round, 

 smooth hole. Extreme durability was essential, and 

 usually proved the source of a machine's failure. 

 The combination of these characteristics into a 

 machine capable of driving the drill rod into the rock 

 with great force, perhaps five times per second, was a 

 severe test of ingenuity and materials. Doane in 1864 

 had three different experimental drills in hand, as 

 well as various steam and water-powered compressors. 



Success finally came in 1865 with the invention of 

 a drill by Charles Burleigh, a mechanical engineer 

 at the well-known Putnam Machine Works of Fitch- 

 burg, Massachusetts. The drills were first applied 

 in the east heading in June of 1866. Although 

 working well, their initial success was limited by 

 lack of reliability and a resulting high expense for 

 repairs. They were described as having "several 

 weakest points." In November, these drills were 

 replaced by an improved Burleigh drill which was 

 used with total success to the end of the work. The 

 era of modern rock tunneling was thus launched by 

 Sommeiller's insight in initially applying pneumatic 

 power to a machine drill, by Doane's persistence in 

 searching for a thoroughly practical drill, and by 

 Burleigh's mechanical talent in producing one. The 

 desperate need to complete the Hoosac Tunnel may 

 reasonably be considered the greatest single spur to 

 the development of a successful drill. 



The significance of this invention was far reaching. 

 Burleigh's was the first practical mechanical rock 

 drill in America and, in view of its dependability, 

 efficiency, and simplicity when compared to the 

 Sommeiller drill, perhaps in the world. The Burleigh 

 drill achieved success almost immediately. It was 

 placed in production by Putnam for the Burleigh 

 Kock Drill Company before completion of Hoosac in 

 1876, and its use spread throughout the western 

 mining regions and other tunnel works. For a major 

 invention, its adoption was, in relative terms, in- 

 stantaneous. It was the prototype of all succeeding 

 piston-type drills, which came to be known generically 

 as "burleighs," regardless of manufacture. Walter 

 Shanlcy. the < Canadian contractor who ultimately 



Figur< 



a. — Trimtroglvcerine blast at Hoosac 

 Tunnel. {Leslie's Weekly, 1873.) 



completed the Hoosac, reported in 1870, after the 

 drills had been in service for a sufficient time that 

 the techniques for their most efficient use were fully 

 understood and effectively applied, that the Burleigh 

 drills saved about half the drilling costs over hand 

 drilling. The per-inch cost of machine drilling 

 averaged 5.5 cents, all inclusive, vs. 11.2 cents for 

 handwork. The more important point, that of 

 speed, is shown by the reports of average monthly 

 progress of the tunnel itself, before and after use of 

 the air drills. 



The right portion of the model (fig. 3) represents 

 the workings during the final period. The bottom 

 heading system was generally used after the Burleigh 

 drills had been introduced. Four to six drills were 



212 



I:' II r TIN 240: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



