would reveal more than Huyghens was able to detect with his unwieldy instrument.
Dominic Cassini soon after discovered a fourth star near the three seen by Huyghens. The four form the celebrated trapezium, an object interesting to the possessors of moderately good telescopes, and which has also been a subject of close investigation by professed astronomers. Besides the four stars seen by Cassini, there have been found five minute stars within and around the trapezium. These tiny objects seem to shine with variable brilliancy; for sometimes one will surpass the rest, while at others it will be almost invisible.
After Cassini's discovery, pictures were made of the great nebula by Picard, Le Gentil, and Messier. These present no features of special interest. It is as we approach the present time, and find the great nebula the centre of quite a little warfare among astronomers—now claimed as an ally by one party, now by their opponents—that we begin to attach an almost romantic interest to the investigation of this remarkable object.
In the year 1811, Sir W. Herschel announced that he had (as he supposed) detected changes in the Orion nebula. The announcement appeared in connection with a very remarkable theory respecting nebulæ generally—Herschel's celebrated hypothesis of the conversion of some nebulas into stars. The astronomical world now heard for the first time of that self-luminous nebulous matter, distributed in a highly-attenuated form throughout the celestial regions, which Herschel looked upon as the material from which the stars have been originally formed. There is an allusion to this theory in those words of the Princess Ida:
"There sinks the nebulous star we call the Sun,
If that hypothesis of theirs he sound."
And in the teaching of "comely Psyche:"
"This world was once a fluid haze of light,
Till toward the centre set the starry tides,
And eddied into suns that, wheeling, cast
The planets."
Few theories have met with a stranger fate. Received respectfully at first on the authority of the great astronomer who propounded it—then in the zenith of his fame—the theory gradually found a place in nearly all astronomical works. But, in the words of a distinguished living astronomer," The bold hypothesis did not receive that confirmation from the labors of subsequent inquirers which is so remarkable in the case of many of Herschel's other speculations." It came to pass at length that the theory was looked upon by nearly all English astronomers as wholly untenable. In Germany it was never abandoned, however, and a great modern discovery has suddenly brought it into general favor, and has in this, as in so many other instances,
