The following tables showing the average rate of progress have been compiled from the actual records made in the tunnels named: +-------------+-------------+--------+--------------+-------------+ | NAME OF | DIMENSIONS |MONTHLY | CHARACTER OF |OBSERVATIONS.| | TUNNEL. | IN FEET. |PROGRESS| MATERIAL. | | | | |IN FEET.| | | +-------------+-------------+--------+--------------+-------------+ |Excavation of| | | | | |headings by | | | | | |hand: | | | | | | | Mount Cenis |10  × 10 | 65.8 |Schist, |Bottom drift.| | Sutro | 6.7  × 5.7 | 70.14 |Quartzose, |... | | St. Gothard | 8.4  × 8.7 | 70.14 |Granite, |Top heading. | | | | | | | |Excavation of| | | | | |headings by | | | | | |machine: | | | | | | | Mount Cenis |10  × 10 | 188.7 |Calcareous | | | | | |schist, |Bottom drift.| | Sutro | 8.15 × 10 | 227.45 |Quartzose, |... | | St. Gothard | 8.4  × 8.7 | 339.45 |Granite, |Top heading. | | Trari | 8  × 9.35| 167 |Gneiss, |Top heading. | | Arlberg | 8.35 × 9.35| 474.2 |Mica schist, |Bottom drift.| | Palisades |16  × 7 | 160 |Trap rock, |Top heading. | | Busk |15  × 7 | 126 |Granite, |Top heading. | | Cascade |16  × 8 | 180 |Basaltic rock,|Top heading. | | Franklin |15  × 7 | 240 |... |Top heading. | +-------------+-------------+--------+--------------+-------------+ The following table shows the monthly progress of completed tunnel in feet excavated through rock: +---------------+--------+----------+------------+ |NAME OF TUNNEL.|PROGRESS|MATERIAL. | METHOD. | | |IN FEET.| | | +---------------+--------+----------+------------+ |Cascade | 207 |Basalt, |Top heading.| |Palisades | 186 |Trap rock,|Top heading.| |Busk | 190 |Granite, |Top heading.| |Tennessee Pass | 169.5 |Granite, |Top heading.| +---------------+--------+----------+------------+ The average monthly progress in feet of excavating tunnels through treacherous ground may be quite generally assumed to be for: (1) clay of the first variety from 43.4 ft. to 60 ft.; for clay of the second variety from 33.4 ft. to 43.4 ft.; for clay of the third variety from 23.3 ft. to 33.4 ft., and for quicksand from 30 ft. to 50 ft. The monthly progress in feet made in sinking the shafts of the Hoosac and Musconetcong tunnels in America was as follows:--