by E. W. (Ethelbert William) Bullinger
by Camille Flammarion
by George C. (George Cary) Comstock
by Charles A. (Charles Augustus) Young
by Sir George Howard Darwin
by Garrett Putman Serviss
by Alexander von Humboldt
by William Tyler Olcott
by Forest Ray Moulton
by Robert S. (Robert Stawell) Ball
by David P. (David Peck) Todd
by Richard A. (Richard Anthony) Proctor
by Denison Olmsted
by Cecil Goodrich Julius Dolmage
by Florence Armstrong Grondal
by Richard A. (Richard Anthony) Proctor
by Henry White Warren
by Garrett Putman Serviss
by David P. (David Peck) Todd
by Sir John Lubbock
by C. V. L. (Carl Vilhelm Ludwig) Charlier
by Erwin Eggert
by Garrett Putman Serviss
by Harold Jacoby
by Simon Newcomb
by S. P. (Samuel Pierpont) Langley
by E. Walter (Edward Walter) Maunder
by James Baikie
by Edward C. (Edward Charles) Pickering
by Thomas Dick
by William Whewell
by Henry Raymond Rogers
by George Ellery Hale
by J. A. (Joseph Anthony) Gillet, W. J. (William James) Rolfe
by Sir Norman Lockyer
by Henry Draper
by Richard A. (Richard Anthony) Proctor
by William Stirling
by William Walker