"Are there not any vacuum powered gyro instruments on a 747? Given a t/s OR a/h, an altimeter, (preferably) an ASI, functioning engines flight controls, flight at night, even after the battery dies should not mean everyone dies screaming surely?"
No vacuum-powered devices on the 744.... unless you include Total Air Temp Probe ops (on ground/low speeds), cargo smoke detection ops, toilet flush, etc....
Standby Airspeed Indicator and Altimeter require no electrics (unless you include AC power for probe heat... not available on Standby Power... only main bus AC/DC). There is a vibrator in the altimeter which uses Main Bat Bus power (but when that fails, the captain can tap the instrument). As previously stated, one of the primary concerns on a "dead ship" would be lack of an attitude indicator (and things that go bump in the night... such as mountains).
Rgds.
NSEU.