In stone masonry, various stones are used depending on their placement and role in the structure. To answer the question about which type of stone in masonry is laid with its length perpendicular to the face of the wall:

1. Understanding Stone Masonry:
   • Stone masonry involves arranging stones to form a robust structure. In this process, stones are laid systematically to ensure stability and durability.
   • Different parts of the stone have specific names based on how they are oriented in masonry.
2. Definition of a Header:
   • A Header stone is placed such that its length extends perpendicular to the wall's face. This means the stone is positioned such that it penetrates into the wall, transferring loads directly into it.
3. Comparison with Other Options:
   • Tail: Not applicable in this masonry context.
   • Stretcher: This is a stone laid with its length parallel to the wall's face, contrasting with the header.
   • Bed: This refers to the horizontal surface upon which stones are laid and not the stone orientation itself.
4. Conclusion:

   Hence, the correct answer is that a Header stone is laid with its length perpendicular to the face of the wall, allowing it to extend into the thickness of the wall. This ensures effective load distribution and wall stability.