The tau or St. Anthony's cross also occurs in some late fifteenth century arms.

The small crosses with which the field of a shield was sometimes powdered were usually what are now called crosslets, but with rounded instead of the modern squared angles, as in the Beauchamp arms (fig. [14]), and a field powdered with these was simply called crusily. But the powdering sometimes consisted of crosses paty, or formy as they were also styled, as in the arms of Berkeley, or of the cross with crutched ends called a cross potent, like that in the arms of the Kingdom of Jerusalem. These crosses often had a spiked foot, as if for fixing them in the ground, and were then further described as fitchy or crosses fixable.

Since the elucidation of the artistic rather than the scientific side of heraldry is the object of this present work, it is advisable to show how it may best be studied.

The artistic treatment of heraldry can only be taught imperfectly by means of books, and it is far better that the student should be his own teacher by consulting such good examples of heraldic art as may commonly be found nigh at hand. He may, however, first equip himself to advantage with a proper grasp of the subject by reading carefully the admirable article on Heraldry, by Mr. Oswald Barron, in the new (eleventh) edition of the Encyclopædia Britannica.

The earliest and best of artistic authorities are heraldic seals. These came into common use towards the end of the twelfth century, much at the same time that armory itself became a thing of life, and they were constantly being engraved for men, and even for women, who bore and used arms, and for corporate bodies entitled to have seals.

Moreover, since every seal was produced under the direction of its owner and continually used by him, the heraldry displayed on seals has a personal interest of the greatest value, as showing not only what arms the owner bore, but how they were intended to be seen.

From seals may be learnt the different shapes of shields, and the times of their changes of fashion; the methods of depicting crests; the origin and use of supporters; the treatment of the 'words' and 'reasons' now called mottoes; the various ways of combining arms to indicate alliances, kinships, and official connexions; and the many other effective ways in which heraldry may be treated artistically without breaking the rigid rules of its scientific side.

Seals, unfortunately, owing to their inaccessibility, are not so generally available for purposes of study as some other authorities. They are consequently comparatively little known. Fine series, both of original impressions and casts, are on exhibition in the British and the Victoria and Albert Museums, and in not a few local museums also,[1] but the great collection in the British Museum is practically the only public one that can be utilized to any extent by the heraldic student, and then under the limitation of applying for each seal by a separate ticket.