...n East Boston. About a mile northeast, Matthew Roberton has discovered silver, which is supposed to be an outcropping from the same vein. On October 15 appears— That silver mine at Spot Pond is progressing favorably. The shaft has been sunk to a depth of 30 feet, and Mr. Harrigan has contracted to carry it 25 feet farther down. It is understood that the yield is satisfactory thus far...