Page:Popular Science Monthly Volume 3.djvu/583

Rh discovery of a starless nebula, or to acknowledge that he had himself fallen into an error on the subject of nebulæ, prevented Galileo from speaking about the great nebula in Orion, we should be compelled to form but a low opinion of his honesty. It happens too frequently that—

That Hevelius, the "star-cataloguer," should have failed to detect the Orion nebula is far less remarkable; for Hevelius objected to the use of telescopes in the work of cataloguing stars. He determined the position of each star by looking at the star through minute holes or pinnules, at the ends of a long rod attached to an instrument resembling the quadrant.

The actual discoverer of the great nebula was Huyghens, in 1656. The description he gives of the discovery is so animated and interesting that we shall translate it at length. He says:

"While I was observing the variable belts of Jupiter, a dark band across the centre of Mars, and some indistinct phenomena on his disk, I detected among the fixed stars an appearance resembling nothing which had ever been seen before, so far as I am aware. This phenomenon can only be seen with large telescopes such as I myself make use of. Astronomers reckon that there are three stars in the sword of Orion, which lie very close to each other. But, as I was looking, in the year 1656, through my 23-feet telescope, at the middle of the sword, I saw, in place of one star, no less than twelve stars, which, indeed, is no unusual occurrence with powerful telescopes. Three of these stars seemed to be almost in contact, and with these were four others which shone as through a haze, so that the space around shone much more brightly than the rest of the sky. And, as the heavens were serene and appeared very dark, there seemed to be a gap in this part, through which a view was disclosed of brighter heavens beyond. All this I have continued to see up to the present time "(the work in which these remarks appear, the "Systema Saturnium," was published in 1659), "so that this singular object, whatever it is, may be inferred to remain constantly in that part of the sky. I certainly have never seen any thing resembling it in any other of the fixed stars. For other objects once thought to be nebulous, and the Milky-Way itself, show no mistiness when looked at through telescopes, nor are they any thing but congeries of stars thickly clustered together."

Huyghens does not seem to have noticed that the space between the three stars he described as close together is perfectly free from nebulous light, insomuch that, if the nebula itself is rightly compared to a gap in the darker heavens, this spot resembles a gap within the nebula. And, indeed, it is not uninteresting to notice how comparatively inefficient was Huyghens's telescope, though it was nearly eight yards in focal length. A good achromatic telescope two feet long