Page:Popular Science Monthly Volume 45.djvu/375

 which is required to have a perfectly smooth surface is placed on huge revolving platforms of cast iron, the surface of which is kept covered with a thin coating of wet sand. The platform, revolving at high speed under the stone, soon rubs it smooth as polished metal—without the polish, however, as bluestone is not susceptible of polish. Other stone is dressed by hand by the stonecutters, who tool it with chisels and axes into different shapes. It is also turned in lathes in the shape of hitching posts, columns, and other forms, while it is susceptible of the most intricate carving, and is used at present in many classes of sculptured work for the ornamenting of buildings. Its extreme hardness makes it proof against all atmospheric changes, and it will neither shell like brownstone nor crumble like marble under the action of frost. It disintegrates and explodes, however, with terrific force under the action of intense heat.

The bluestone formation of New York State lying in Ulster County belongs to the Hamilton period, while that quarried in the other counties mentioned belongs to the Catskill group of rocks of the Upper Devonian age. As far as the writer has been able to learn, minerals are never found in the bluestone deposits, except in the form of oxides. Ignorant prospectors have at times reported the discovery of anthracite coal, which, however, has always proved to be a worthless deposit of organic slate, which in some localities abounds in considerable quantities. It is improbable that coal will ever be found in this region, as the stone formations that lie nearest the surface are those which underlie the coal measures of the entire country.



N all the history of modern scientific progress there is no more beautiful instance of the way in which the torch of knowledge is passed from hand to hand as generation succeeds generation, each holder adding his increment of light to the flame, than that to be seen in the interlinking of the work of Lady Mary Wortley Montagu and Edward Jenner with that of Pasteur and Lister and Koch, and the multitude of illustrious seekers now striving to reveal to us the whole world of man's microscopical friends and enemies. It is to be noted that in each individual case the mind that was to aid in setting forward the hand on the dial of progress was specially gifted for its work, so that when the new truth was presented to it, it was like the seed that fell on 