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He wrote asking him to look at some other objects and describe them. When the description was received it was found to be exact. No doubt could remain. The result was a further correspondence, the purchase by Mr. Dawes of the largest and best instrument that Mr. Clark could then make, and a friendship which continued as long as Mr. Dawes lived.

Mr. Clark now secured recognition in his own country and became ambitious to make the largest refracting telescope that had ever been known. This was one of eighteen inches diameter, which was completed about I860 for the University of Mississippi. While testing it at his workshop, a discovery of a most interesting character was made with it by Mr. George B. Clark, the son. This was a companion of Sirius, which had been known to exist by its attraction on Sirius, but had never been seen by human eye. The breaking out of the Civil War prevented the University of Mississippi from taking the telescope, and the latter was acquired by citizens of Chicago. It is now mounted at the Northwestern University in Evanston, Ill.

The making of disks of glass of larger and larger size was continued by the great glass works of Chance & Company, in England. But they found the work too delicate and too troublesome, and allowed it to pass into the hands of Feil of Paris, son-in-law of Guinand. With the glass supplied by these two parties, Mr. Clark made larger and larger telescopes. First was the twenty-six-inch telescope for the Naval Observatory at Washington and a similar one for the University of Virginia.