A knowledge of metals and of their qualities is a desirable accomplishment which all metal-workers and founders should possess, and it was doubtless because some of the early bellfounders intuitively, or as the result of accidental experiment, discovered the true properties of the alloys they used that they were able to excel in the craft. There are secrets associated with the mixing of the metal, too, especially that of heating the molten metal to the correct temperature at the most critical moment of running it into the mould. Much depends also upon tuning the bells by turning and reducing their thicknesses at the right place in the bell's cone. The accuracy of such details is essential, otherwise those mellow sounds for which many of the old bells are noted would be absent. It is true that the rich mellowness and musical notes so noticeable in some peals are due to some extent to age, the exact influence of which is not fully understood. The bellfounder has always regarded his work from a lofty standard, and has recorded the accomplishment of any great work by the inscriptions he has caused to be cast upon the surface of the bell. Such data is often accompanied by the name and trademark of the founder, the Bellfounders' arms being frequently added. Sometimes such inscriptions are dated; at others the lettering is sufficient to denote the date of the work. The making of great bells was always regarded as an event of some importance. Most of those which have obtained historic fame have either been associated with some public use or have been cast for ecclesiastical purposes. Such events were often attended by kings and queens and great ecclesiastics, who threw into the melting-pot contributions of silver and gold, inscriptions upon the bells themselves often recording the special object of their manufacture. The difficulties in the way of casting bells a distance away from the tower where they were to be hung often induced the founders to cast them on the spot; indeed, as late as 1762 the clock bell of Canterbury was recast in the Cathedral yard. Great Bells of Historic Fame. There are many great bells of historic fame, and others which have gained notoriety from their great size. The claim to the possession of the largest bell was formerly made by the Chinese, but the palm is usually accorded to the Great Bell of Moscow, which measures 19 ft. in height and 64 ft. in circumference. In our own country there are the Great Bell of St. Paul's, weighing five tons; "Great Tom" of Lincoln, of similar weight; "Peter" of York, weighing ten tons; and "Big Ben" of Westminster, scaling fourteen tons.