THE COMSTOOK LODE 41 



lingering traces of solfataric action. Chemical decomposition is yet active 

 here. The vast masses of propylite horses and of clay are to-day quite plastic 

 and working with immense dynamic power. Nearly the whole interior of the 

 lode is in a condition of gentle chemical activity. 



Atlas-Plates 3, 4, and 5, are horizontal maps of the underground work- 

 ings on a scale of 100 feet to the inch. The shaft-mouths are indicated by 

 small parallelograms ; the separate compartments are crossed, except the 

 pump-shaft, which is a simple square in black, drawn to the scale of the shaft- 

 section ; winzes and inclines, which connect subterranean levels, are in plain 

 black ; tunnel-dumps are indicated by half-circles of hachures. Each drift is 

 marked by a separate color, which continues through all three sheets, at an 

 approximately corresponding level. The drifts are numbered, first, according 

 to their depth from their own shaft-mouths; secondly, in brackets with a sepa- 

 rate number indicating the depth below a general datum-point situated upon 

 the Gould and Curry outcrop, back of Virginia City. Atlas-Plates 6 and 7, 

 and Fig. I, Atlas-Plate 12, are longitudinal elevations, on a scale of 200 feet 

 to the inch, on which the mine-workings and ore-bodies are delineated as if 

 the vein-materials were transparent. Atlas-Plates 8, 9, and 10 are vertical 

 cross-sections, also at 200 feet to the inch, looking north, and cut from east to 

 west at all important parts of the lode, and colored so as to show its geology. 

 Nos. 11 and 12 are horizontal sections on illustrative levels, also colored geo- 

 logically. 



The Gold Hill Group. — Atlas-Plate 3 embraces 4,300 feet of the 

 southern end of the lode, from the furthest workings of the Uncle Sam to 

 the north Alpha line. It will be seen that this map lacks a few important 

 features, such as the drifts in the mines of Gold Hill proper, which were 

 scarcely ever surveyed at all, and of which, when measured, the records were 

 not preserved. 



Considerable exploration-work has been done in the Alpha, but, like the 

 adjoining group of claims, it has no full map. Fortunately, the geological 

 features are quite well understood, so that all questions affecting the general 

 structure of the lode are not obscured by ignorance of the workings. 



From the south end of the Uncle Sam the mass of the lode, following 

 6 



