1739.The general history of China by Du Halde.

The general history of China. Containing a geographical, historical, chronological, political and physical description of the empire of China, Chinese-Tartary, Corea, and Thibet. Including an exact and particular account of their customs, manners, ceremonies, religion, arts and sciences .. (1739)
Author: Du Halde, J.-B. (Jean-Baptiste), 1674-1743; Brookes, Richard, fl. 1750. tr
Publisher: London, J. Watts
http://www.archive.org/details/generalhistoryc03haldgoog

Text: Sea of Japan.
http://www.archive.org/stream/generalhistoryc03haldgoog#page/n343/mode/2up/search/japan
After travelling eighty Lys Eastward we found the Valley considerably enlarged, and it formed a plain above a League in Diameter: We crossed this plain travelling toward the North-east, and passed over the River, on the Banks of which we saw a great quantity of large Pieces of Wood, chiefly Fir proper to build with; they let it float down this River when it is most full of Water towards the Sea of Japan, then transport to another River, and guide it within a Day's Journey of Peking:This makes Wood for building very reasonable, tho' there is a great Consumption of it, the Wood-work of the Houses taking up a great quantity.