[expand]The crown (tono) was compression ring forming roof’s central opening. This wooden hoop—typically 1.5 to 2 meters in diameter—was structural keystone supporting entire roof system through elegant engineering. The crown’s outer edge featured mortises or holes accepting roof poles (uni), the number varying by yurt size but typically 60-100 poles. The crown’s inner surface might be carved or decorated, visible from interior as ceiling’s focal point. The weight was substantial—5 to 15 kilograms depending on size—requiring careful lifting during assembly.
The roof poles radiated from crown to lattice wall top, creating conical roof profile. Each pole was bent slightly, giving roof graceful curve rather than straight-line cone. The bending was achieved by steaming or slow mechanical pressure during seasoning, permanently setting curve. The poles’ lower ends rested on lattice wall, their weight helping secure wall sections together. The upper ends inserted into crown mortises, creating rigid connection. The total weight of 60-100 roof poles concentrated on crown created enormous compression force, the crown’s circular geometry distributing this load evenly preventing collapse.
The assembly required proper sequencing. The lattice wall was raised first, then crown was lifted into approximate position, supported temporarily by forked poles or human holders. The roof poles were inserted one at a time—lower end placed on lattice, upper end lifted and slotted into crown mortise. The initial poles were precarious, requiring careful balance, but as more poles were added the structure became increasingly stable. The final poles sometimes required forcing into place as accumulated tension in structure made insertion difficult. Upon completion, the crown was self-supporting, held aloft by compression forces distributed through roof pole array.
The central opening served multiple functions. Smoke from hearth fire escaped through opening, preventing interior smoke accumulation. Light entered, illuminating interior during day. The opening could be partially or completely covered using felt flap attached to adjustable poles, allowing smoke escape while limiting rain entry, or closed completely during heavy precipitation. The opening’s size was critical—too large allowed excessive heat loss and rain entry, too small caused smoke backup, optimal sizing balanced these concerns.
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