Re: English rail at Last Chance and SP&N
A word (or two) on the Sacramento Placer & Nevada (in response to your call the other night). When that railroad was built with the overt aid of the principals of the SVRR, it was fully expected that it would serve as the second link in a line of railroads which would evenutally reach clear across the Sierra Nevada. This is delineated in a Simon Elliott map of 1860 (which was published in a Library of Congress book of early railroad maps. Elliott having been the one to have surveyed both the SP&N line to Nevada City and the line eastward thence to Henness Pass–and, ironically, the first one to have surveyed the Donner route).
While the SP&N was initially surveyed to merely connect Auburn with the then railhead at Folsom, it was built during the height of the Comstock excitement–by which time the route had been surveyed with some care to Nevada City and (with no doubt less care) beyond Henness Pass. The SP&N was an aspect of the private-money free-enterprise effort to connect the Sacramento with the Missouri which had been incrementally progressing since earth was turned on the Pacific Railroad in 1850. The SP&N (in particular, and the whole free-enterprise Pacific railroad in general) was outflanked–literally and figuratively–by the government-supported CP.
While Judah had essentially nothing to do with the SP&N (it killed his own Centralia/California Eastern scheme), I believe he initially envisioned that the CP would commence from the head of the SP&N. It did not; essentially for one simple reason: the Pacific RR act required (initially) that the CP build 40 miles on their own dime. Once the CP folks thought about it, it was obvious that 40 miles commencing at Auburn Station would cost one hellofa lot more than 40 miles commencing at Sacramento due to the relative higher cost of building railroads in the mountains vs. the flat valley. Thus the SP&N and SVRR were marginalized.