2. When new materials enter the market, they first imitate the product they replace. Early plastics imitated wood. Early vinyl imitated leather. Early concrete was marketed as "artificial stone." Only after a new product has gained acceptance by imitation is it free to develop its own identity. In the early years of San Francisco, most all walks were redwood. Only the wealthiest could afford paving in stone. In the mid-1800s, concrete was (re)invented and began to appear as a cheaper and therefore more accessible alternative to natural stone. Anytime you see 'artificial stone' in a patent stamp, like this one at 23rd and York streets, you know it's very early concrete and likely from when the walk was cast for the first time.
3. I knew that Manhattan and Chicago had steam utility companies that sell steam as a power source. How steampunk, right? I didn't know that downtown San Francisco had an active steam utility company. This manhole cover at Lombard and Sansome streets came as a surprise. Steam is sold to downtown companies and buildings to use for industrial processes and as radiant heat. The steam is pumped through the walls of local buildings to heat them. It offers a very efficient form of heat and frees the building from having to provide space for its own boiler. You can find a map of SF's steam system here.
4. The Alameda-based Spring Valley Water Company (SVWC) held a monopoly on San Francisco's water supply from the mid-1800s until it was replaced by the San Francisco Water Department in 1922 during completion of the Hetch Hetchy Dam. This water utility box cover at Capp and 24th streets and others like it have really striking star treads.
5. In 1896, the San Francisco Gas Light Company merged with the Edison Light and Power Company to form the San Francisco Gas and Electric Company. SF G&E dissolved in 1903, and operations were taken over by PG&E in 1905. This cover at 23rd and Alabama streets is for a well where gasoline "drip" condensate is cleared from natural gas lines.
6. This one is driving me nuts! "U. E. & G. Co" at 21st and Capp streets — Union Electric and Gas Co.? United Electric and Gas Co.? The treads are reminiscent of early industrial rivets, and it's definitely pre-PG&E. Usually if there's no Wiki reference, there are at least a few references to obsolete companies in period trade publications like the turn of the century Public Utility Reports, or trade journals and directories. But in this case, I seem to have come to a dead end. If anyone knows, please contact me.
7. Union Railroads of San Francisco, "URR," operated under many names including Market Street Railroad Company (a horse-drawn incarnation began in 1857), and Market Street Cable Railway Company (after the company converted to cable drawn cars beginning in 1882). The electrically powered company operated as Union Railroads from the turn of the century and most of the teens until 1918 when it became Market Street Railway, the company that operates the vintage cars that run on Market Street today. This utility vault manhole cover can be found at Webster and California streets.
8. Here's an interesting incongruity. A 1907 directory lists the address of this contractor, T.J. Egan, as 503 Castro. The iron-cast sewer vent cover at 20th and Guerrero streets here clearly reads 305 Castro. How funny to discover a 100-year-old typo. I wonder if Egan paid for the listing (or the casting). I wonder if he raised hell over it.