You can access Google Street View within the Photo Ephemeris Web app by dragging and dropping the orange figure at the bottom right of the map:
Once you start dragging you’ll see available StreetView locations shown as blue overlays on the map:
If you drop the orange figure onto one of these, the map will show Street View. You can look around by clicking the navigation arrows shown in the image:
Exit StreetView by clicking at the top left of the map as shown above.