Historic road construction principle: Who stated that stone size used in a road should not exceed about 2.5 cm in any dimension because the wheel contact length on a smooth level surface is roughly 2.5 cm, and larger stones are “mischievous” for the running surface?

Introduction / Context:
Classical road builders proposed distinct philosophies for pavement layers and stone size. Understanding who advocated which principle helps in remembering construction methods like Telford’s large hand-packed stones vs. Macadam’s small broken-stone surface.

Given Data / Assumptions:

• Quotation emphasizes limiting stone size to about 2.5 cm (1 inch).
• Focus is on the wearing surface and wheel contact characteristics.
• Historical figures: Telford, Macadam, Tresaguet, Sully.

Concept / Approach:
John Loudon McAdam revolutionized road building by insisting on well-graded, small broken stones, compacted to form an impermeable, stable surface. He explicitly argued against large stones on the running surface, declaring them harmful (“mischievous”).

Step-by-Step Solution:

Verification / Alternative check:
Historic literature on “macadamized” roads cites the 1-inch (≈2.5 cm) maximum size for surface stones to ensure tight interlock and fine running quality.

Why Other Options Are Wrong:
Telford and Tresaguet used larger foundation stones; Sully is not associated with this specific principle.

Common Pitfalls:
Assuming all pioneers endorsed the same stone sizes; mixing up foundation versus wearing course specifications.

Final Answer:
Macadam