The rapidly increasing use of guano, in the United States, and the growing conviction upon the public mind, that it is the cheapest and best purchasable manure in the world, together with the fact of a great want of information among American farmers, as to the best mode of applying it to the soil, has induced the agents of the Peruvian Government for the sale of guano in the United States, to employ the author of this pamphlet to collect and publish such information. It is hoped the favorably and well known name of the author, as an agricultural writer and traveller, together with his extended opportunities of witnessing the application and effect of guano upon the various soils and climates of this country, will give this work such a character, as to induce every improving farmer, gardener, or horticulturist, in America to give it a careful perusal. The author believes it will be found to contain all and much more than its title imports, and be of great value to every person using or dealing in guano; as the analysis, not only of the pure article is given, but that of several specimens of adulterated samples, so as to enable the farmer to avoid being cheated by base counterfeits. The author will be much obliged to any gentleman who will furnish him for publication in future editions of this work, or in the columns of The Agricultor, any details of experiments in the use of Peruvian guano, which will be useful to the farmers of this country, as it is his desire, as well as the guano agents, to give them useful facts; not only to increase the sale, but the fertility of the land, and wealth of the owners.