Provided, That in case any foreign country or dependency shall, either
directly or indirectly, impose upon pine, spruce, elm, or other saw logs,
or round unmanufactured timber, pulp wood, stave bolts, shingle bolts,
or heading bolts, an export duty, discriminating crown dues, ground
rents, customs regulations, or other duty or tax, when such articles, or
any of them are exported or intended for export to the United States
from such country or dependency, then a duty of 25 per cent ad valorem
upon the lumber mentioned in this paragraph shall be levied, collected,
and paid in addition to the duty herein imposed when the same is imported
from such country or dependency.

Provided, That if any country or dependency shall impose an export duty
upon saw logs, round unmanufactured timber, stave bolts, shingle bolts,
or heading bolts, the amount of such export duty shall be added, as an
additional duty, to the duties imposed upon the articles mentioned in this
paragraph when imported from such country or dependency.