HAND-BOOK OP WASHINGTON. 87 Marshall and Jackson, Webster, Clay, and John Quincy Adams; and those who take pleasure in studying tho peculiarities of an interesting negro population cannot fail to be amused by a morning walk in and about the Centre market when busi ness is in full blast. THE CLIMATE OP WASHINGTON. An erroneous opinion has for many years pre vailed respecting the healthfulness of this city,— the grave yard records having conclusively proven the fact that there are very few more healthy localities in the Union. The climate resembles that of the adjoining States of Maryland and Virginia, and may be denominated as temperate. Many winters come and go without bringing a bit of snow, although the winter of 1855-6 will ever be remembered for its many severe snow storms and its excessive coldness. The summers are long and oftentimes oppressive, but the air is kept pure by frequent thunder storms. During the autumn, on the immediate banks of the Potomac, bilious and intermitting fevers prevail to a considerable extent, but the malarian influences do not last long, and those who have been acclimated are