Drawing by R.W. Porter showing an astronomer seated at the prime focus of Mount Palomar Observatory's 200-inch telescope, 1940

Photograph of a drawing by R.W. Porter showing an astronomer seated at the prime focus of Mount Palomar Observatory's 200-inch telescope, 1940. A slanted view of an astronomer peering through the eyepiece of a 200-inch telescope. The pedestal of the telescope, which is also shown, is drawn to reveal the inner workings of the apparatus by showing layers of depth. On the bottom right of the image there is a cut-away panel showing a broader layout of what appears to be the entire telescope. The circular bottom of the chair can be seen through the illustration of the man.