Page:Popular Science Monthly Volume 5.djvu/281

Rh instruments are hardly comparable. Indeed, drawings by different observers, with the same instrument, and made at the same time, are often as different from each other as any of the previous drawings from Lord Rosse's.

The resolvability of the nebula is claimed by Lord Rosse, but the testimony of the spectroscope, as far as that goes, is against that inference, and the testimony of large telescopes, at least equal to Lord Rosse's in their defining power, is likewise unanimously contrary.

Any one, who will critically study the drawings named above, will, it is believed, arrive at the conclusion that no traces of resolvability have been fairly made out. Changes of form, although the evidence of the various drawings is seemingly in favor of such changes, are not probable, from a comparison of all the data. The drawing of Bond is confirmed, we believe, by Safford, of Chicago, by aid of the 18 1/2-inch refractor, and by the great refractor of the Naval Observatory at Washington, so far as an examination has been made, and



after a careful collation of all drawings; the only inference it seems possible now to draw is as to the enormous personal differences of the artists. It should be remembered that the difficulty of getting a correct drawing engraved correctly is itself immense, and not often to be overcome, especially if the engraver has not himself studied the nebula which he is to represent.