SAM D.--Gillespie's work on surveying will probably meet your need. * * * * * F. A. L.--RED INK.--Boil two ounces of Brazil-wood, half an ounce of alum, half an ounce of crystals of tartar, in sixteen ounces of pure water till the water is reduced one-half. Dissolve in the strained liquor half an ounce of gum-arabic, and add one and a half drams of cochineal powder digested in one and a half ounces of alcohol. This will make a beautiful, permanent ink. But if you prefer, you may take this somewhat easier way: Dissolve an ounce of cochineal powder in half a pint of hot water. When cold, add a quart of spirits of hartshorn. Dilute with three ounces of water. Let it stand a few days, and then pour off the clear liquid. * * * * * INTERESTED FRIEND.--Gordon's _Electricity and Magnetism_, the last edition of Ganot's _Physics_, Deschand's _Physics_, and Guthrie's _Electricity and Magnetism_ can be comprehended by the ordinary high-school boy. The school text-books on natural philosophy, as, for instance, Cooley's _New Natural Philosophy_, give much that is easily understood. * * * * * HUMPTY DUMPTY.--The earliest posts for carrying letters between Brussels and Vienna were established in 1516 by Franz, Prince of Thurn und Taxis. His descendants enjoyed the monopoly until 1806, on the dissolution of the German Empire. The present Prince has a palace in Ratisbon, a very ancient city of Bavaria. It is sixty-nine miles north of Munich, on the right bank of the Danube. Its cathedral was founded in 1275, and completed in 1875. The abbey of St. Emmerau, the patron saint of the city, was enlarged by Charlemagne. In the rear of his palace the Prince of Thurn und Taxis can see a monument to Kepler, the astronomer, whose remains lie in the Protestant burial-ground. * * * * * E. T.--FIRST BISHOP OF LIVERPOOL.--The diocese of Liverpool was recently formed mainly out of Chester. Its bishop is the Rev. John Charles Ryle, D.D. He was nominated by Lord Beaconsfield, and was consecrated in 1880. He is known as the author of some excellent books of a devotional tendency, and as a commentator on the Gospels. * * * * * COUNT NO ACCOUNT.--The address for which you inquire was published in the Post-office Box, No. 82, HARPER'S YOUNG PEOPLE. * * * * * BICYCLING. All boys who have asked questions concerning the price of bicycles are referred to the advertisements of the Pope Manufacturing Company, of Boston, and E. I. Horsman, of New York, on the last page of the cover of YOUNG PEOPLE. R. B. SWEET.--You can buy bicycles with front wheels of from 28 to 42 inches in diameter, with rubber tires and steel spokes, for from $12 to $35. GEORGE L. HALL.--See preceding answer for your first question. Only bicycles with rubber tires and careful finish can be driven up hill.