Of course there were not people wanting who ascribed this wonderful discovery of Herschel's to pure chance. If he hadn't just happened to turn his telescope in that particular direction on that particular night, he wouldn't have seen this Georgium Sidus they made such a fuss about at all. Quite so. And if he hadn't built a twenty-foot telescope for himself, he wouldn't have turned it anywhere at any time. But Herschel himself knew better.