Thanks, cajunscot. There is a bit of discussion of America and immigration in both documents. They really are very interesting, though I enjoy Boswell's journal descriptions more.

From the book I cited, here is what Johnson writes about the dance, and it points out the interesting effect of reading both accounts:

When it was time to sup, the dance ceased, and six and thirty persons sat down to two tables in the same room. After supper the ladies sung Erse songs, to which I listened as an English audience to an Italian opera, delighted with the sound of words which I did not understand.

I inquired the subjects of the songs, and was told of one, that it was a love song, and of another, that it was a farewell composed by one of the Islanders that was going, in this epidemical fury of emigration, to seek his fortune in America. What sentiments would rise, on such an occasion, in the heart of one who had not been taught to lament by precedent, I should gladly have known; but the lady, by whom I sat, thought herself not equal to the work of translating. (42)