The crude material of earth being used, each portion requires careful refining from natural impurities, and when compounded, being dependent upon combustion in the furnace for its completion, (which combustion is effected by change of the atmosphere beyond the power of man to direct, but exercises a power to affect the heat of the furnace acting for good or for evil,) much responsibility rests upon the furnace-tenders; constant care on their part is required. A slight neglect affects the quality of the glass. A check upon the furnace in founding-time will spoil every pot of metal for the best work. Overheat, too, will destroy the pots, and the entire weekly melt will be launched into the cave, at a loss of several thousand dollars. Even with the utmost care, a rush of air will not uncommonly pass through the furnace and destroy one or more pots in a minute's space. And when the furnace has yielded a full melt, and is ready for work, many evils are at hand, and among the ever-jarring materials of a glass-house, some one becomes adverse to a full week's work; vigilance is not always the price of success. Again: no branch of mechanical labor possesses more of attraction for the eye of the stranger or the curious, than is to be witnessed in a glass-house in full play. The crowded and bee-like movements of the workmen, with irons and hot metal, yet each, like the spheres of his own orbit, presents a scene apparently of inextricable confusion. It is a difficult task to describe the curious and interesting operations of the glass-blowers; for the present we may say, that there is no other employment so largely dependent upon steadiness of nerve and calm self-possession. The power of manipulation is the result of long experience. The business of the glass-blower is literally at his "fingers' ends." It is most interesting to witness the progress of his labor, from the first gathering of the liquid metal from the pot, and the passing it from hand to hand, until the shapeless and apparently uncontrollable mass is converted into some elegant article. Equally interesting is it to witness with what dexterity he commands, and with what entire ease he controls the melted mass; the care, also, with which he swings it with force just enough to give it the desired length, joins it to other pieces, or with shears cuts it with the same ease as paper. The whole process, indeed, is one filled with the most fascinating interest and power. Of all the articles of glass manufacture, none command a greater degree of attention than the article called the salver, and no other develops so pleasing and surprising effects in its processes. When seen for the first time, the change from a shapeless mass, the force with which it flies open at the end of the process, changing in an instant into a perfect article, all combine to astonish and delight the beholder.