discouraged that they sold out their leases and disbanded. Both Townsend and Drake would have died richer men had they never heard of the Pennsylvania rock oil. THE CLARKS AND THE TELESCOPE. [Illustration: Alvan Clark.] The fame of American telescopes is due to the work and inventions of the Clark family of Cambridgeport, Mass., the descendants of Thomas Clark, the mate of the Mayflower. The founder of the great--in a scientific sense--house of Alvan Clark & Sons, telescope-makers, was a remarkable man. Until after his fortieth year he devoted himself to portrait-painting. In 1843 his attention was accidentally turned toward telescope-making. One day the dinner-bell at Phillips Academy, Andover, Mass., happened to break. The pieces were gathered up by one of Clark's boys, George, who proceeded to melt them in a crucible over the kitchen fire, declaring that he was going to make a telescope. His mother laughed, but his father was deeply interested and helped the boy make a five-inch reflecting telescope which showed the satellites of Jupiter. This was the beginning of telescope-making in the Clark family, an industry which has given to the scientific world its most remarkable lenses. Alvan Clark dropped his paintbrushes, never to take them up again until at the age of eighty-three he made an excellent portrait of his little grandson. To Alvan G. Clark, the present head of the house, are chiefly due the scores of devices by which American ingenuity has surpassed the slower European methods. The delicacy required in the manipulation and grinding of the immense lenses made by the Clarks is almost incredible. The latest triumph of the firm--a forty-inch lens for the Spence Observatory at Los Angeles, Cal.--required two years of grinding and polishing after a piece of glass perfect enough had been obtained. So delicately finished is it that half a dozen sharp rubs with the soft part of a man's thumb would be sufficient to ruin it. Alvan G. Clark is now a man sixty-one years-old. He has lived all his life at the home in Cambridgeport. His greatest sorrow is that there is no son of his to carry on the work after his death. His only son died a few years ago, just as he was beginning to show wonderful aptitude in the art which has made the family famous in all the great observatories of the world. JOHN FITCH AND OLIVER EVANS--STEAM TRANSPORTATION. In looking over the work done by American inventors, the great names are those to be found at the heads of the preceding chapters. But the list is by no means exhausted. Among the early men of achievement in the field of invention I have had to omit at least a dozen whose work deserves more than a paragraph. The history of the steamboat is not complete without reference to John Fitch.