While the earliest attempts to detect photographic spectra of galaxies—by
Huggins (1888), Scheiner (1899), and Fath (1908)—showed only limited success,
in the period from ~1906 to 1912 Slipher (1913) made great strides to improve
both the signal-to-noise and the stability of his spectra. Only by doing so was
Slipher able to measure the first galaxy Doppler shifts. I will briefly review
from a technical perspective the steps involved: photographic sensitization,
nebular spectrograph design, and consistent observing methods. By identifying
fast spectrograph camera lenses as the key component in nebular spectrographs,
Slipher pointed the way for Mt. Wilson astronomers Humason and Hubble to
confirm the velocity-distance relationship in the period 1928 to 1931.