Epigraph
Section of the Primitive Mounting
SPECTRAL IMAGES OF STARS, THE UPPER LINE SHOWING HOW THEY APPEAR WITH THE EYE-PIECE PUSHED IN, THE LOWER WITH THE EYE-PIECE DRAWN OUT
THE GREAT REFRACTOR OF THE NATIONAL OBSERVATORY AT WASHINGTON
The “Broken-Backed Comet-Seeker”
Nebula in Orion
Dip of the Magnetic Needle in Various Latitudes
Star Spectra
PROFESSOR LANGLEY’S AIR-SHIP