344 THE POPULAR SCIENCE MONTHLY. 



nouncement was exj^ected that it was completed, or at least only 

 required the final finishing touches. Suddenly a telegram arrived — 

 an ominous thing. Was it to announce an imperfect figure ? This 

 would be a most annoying thing, for it would require the whole to be 

 reground and repolished. But no, it was very brief, but it announced 

 a terrible misfortune. It was a pressing request to come down at 

 once. The lohole speculmyi had burst i?ito a thousand pieces. 



It was a terrible blow, for it was the very misfortune which had 

 been prognosticated by the English manufacturers and by the greater 

 number of astronomers, including those who had had much experience 

 in the construction and use of specula. The explosion had been ter- 

 rific. The whole workshop was covered with jagged, torn masses of 

 glass, varying in weight from ten or twelve pounds to an impalpable 

 dust. Mr. Calver had had a narrow escape, but he and his workmen 

 escaped without serious injury. The monetary loss was great, and bade 

 fair to be greater, for with the loss of the speculum the rest of the 

 telescope became useless. It might well seem that they were right 

 who held the view that large silver-on-glass specula were impractica- 

 ble, as from the difficulty in annealing large masses of glass they might 

 be expected to break at any moment. 



Within an hour or two of receiving the telegram announcing this 

 terrible mishap Mr. Common was in the library of the Royal Astro- 

 nomical Society. While there he was met by a friend, a fellow astron- 

 omer, who, being aware that news was daily expected of the com- 

 pletion of the great speculum, asked him for the latest intelligence. 

 Mr. Common calmly handed him the fateful telegram. He was thun- 

 derstruck, for it was so unexpected, and he was one of those who had 

 looked for much gain to astronomy to accrue from the construction 

 and subsequent employment of this grand new instrument. After 

 expressing, no doubt imperfectly enough, his sorrow, sympathy, and 

 disappointment, he naturally put the question, "What can you do 

 now ? " The answer came gently enough : " Do ? Why, I have tele- 

 graphed over to Paris to see if I can't get two more disks of glass. 

 It will be one to spare in ca-se of another explosion." 



Success must crown indomitable courage like this. The new disks 

 arrived, and were duly transferred to Mr. Calver. One was selected, 

 and, after much labor, ground, polished, and finished. The remaining 

 portion of the instrument and the observatory were pushed on as 

 quickly as possible. On August 1, 1879, the instrument was complete, 

 and the grandest and most powerful telescope in existence stood 

 finished before its maker, designer, and owner. 



An instrument of this large aperture will take a long time to thor- 

 oughly test, but it has stood triumphantly all the tests which have 

 been applied hitherto. It has been tested on the moon, a most crucial 

 test in experienced hands, on Jupiter and Saturn, and on faint com- 

 panions to bright stars. In all cases satisfactory results have been 



