Diagrams to explain the square-set timbering technique

While writing THE BONANZA KING, I became fascinated with the techniques and technology of Comstock mining. Here are some diagrams to help explain the square-set timbering technique invented in late 1860 by mining engineer Philipp Deidesheimer that made it possible to extract the Comstock Lode’s colossal ore bodies. The internal structure of a honeycomb gave Deidesheimer the crucial inspiration.

(Clicking on the images should enlarge them for more detailed examination.)

This diagram clearly shows how “wall plates” and “angle braces” were used to shore a “dipping” ore body:

This next one shows how miners could use the square set technique to stope out ore in depth, on multiple “floors” (each line of square sets) and “levels” (from each of the shaft stations, generally at 100 foot intervals) at the same time.  Comstock miners thus gutted an ore body with speed that would have astonished previous generations of miners:

Next is a similar one from the Mining & Scientific Press, June 13, 1891, that shows how square sets could “grow” in an upraise or winze (working down) on the dip of an ore body.

Below is a standard Comstock mineshaft as they were constructed once “second line shafts” started going down. (Those were the shafts that were sunk east of the “croppings,” prime examples being the Gould & Curry’s “Bonner Shaft,” the Savage’s “Curtis Shaft,” and the “Fair Shaft” at the Hale & Norcross. Those three were named for the men who superintended their “sinking.”) They had three or four compartments. Two compartments for hoisting, one for pumping, and one for sinking. Three compartment shafts omitted the sinking compartment, the one through which the work of sinking the shaft to another station was done. It’s apparent that Deidesheimer’s square set technique inspired their construction. If you look carefully, you can see the “guide rods” running down the sides of the two hoisting compartments and the sinking compartment. The guide rods were embraced by the “ears” of the cage frames, iron flanges that guided the cages up and down the shafts. (I’ll go into greater detail on the shafts, cages, and hoisting and pumping apparatuses in another post.)