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Life and Works
object viewed, and with sketches and diagrams which gave the position of the small stars in it and near it.[1]
As the nebulæ and clusters were discovered they were placed in classes, each class covering those nebulæ which resembled each other in their general features. Even at the telescope Herschel's object was not discovery merely, but to know the inner constitu-
- ↑ Thus the position of small stars critically situated in the centre, or on the edges of the nebulæ was always noted. Many of the descriptions are given in the published papers, but the publication of the diagrams would be an immense help to this branch of astronomy. D'Arrest in his reduction of Herschel's nebula observations (1856) writes: "Gewiss wäre es vom höchsten Interesse für die Entwickelung, welche hoffentlich auch dieser Zweig der beobachtenden Astronomie zukünftig erhalten wird, wenn die Herschel'schen Beobachtungen in der Ausführlichkeit in welcher sie, verschiedenen Andeutungen zufolge, handschriftlich vorhanden sind, veröffentlicht würden. Es schliesst sich dieser Wunsch in Betreff der Nebelflecken lebhaft an den an, welcher, schon vor einem Jahrzehnt nach Veröffentlichung der 400 noch unedirten star-gauges von gewichtigerer Seite her geäussert wurde." In this all must agree who have a knowledge of the direction in which we must look for advances in the difficult and important questions of the distance, the motions, and the changes of the nebulæ. Almost the only aid to be looked for from the older observations must come from such diagrams, and we may safely say that the publication of this priceless material, just as it stands, would carry our exact data back from 1833 to 1786, or no less than forty-seven years.
