My new car is a 1948 Chevrolet Fleetmaster. Only has 38,500 miles on the odometer and I believe it is accurate.

But what is the large glass bottle on the firewall, driver side? It has vacuum lines attached but I can't find any controls or switches for it.
A windshield washer maybe? But again, I see no evidence of a spray nozzle at the windshield.

I know its not an addition to the radiator as is often done. Because this car has one of those on the other side of the firewall.

See pics

That is for windshield washers, my 47 has them and on mine there is a button on the lower edge of the dash left of the heater switches. There should be 2 vacuum hoses, one from the engine and one to the top of the jar. When vacuum is applied it it lifts the diaphragm and then when you let off the button the spring in the diaphragm forces the washer fluid out.

Thanks dens41, this is very helpful. You solver another mystery: What that chrome button under the dash, next to heater controls is for.

There should also be little nozzles on the side of the wiper transmission

I can see from the pictures you have the spray nozzles on the wiper transmissions. They are the little sprayers on the inner side of the wiper transmissions.