Plow, self-sharpening, [45]
Police force of Chicago in 1847, [70]
Polish female laborers, [197]
Pompeii, bread found in ruins of, [234]
Poorhouses used as storehouses for wheat, [230]
Portugal, [241]
Post-office, Chicago, in 1847, [70]
Postage in 1831, [50]
Postage stamps, [70]