SCHUYLER.--1. A vacuum air-brake, of which there are several patterns, is a kind of continuous brake, operated by exhausting the air from some appliance under each car, and so causing the pressure of the atmosphere to apply the brakes. 2. Nos. 4, 5, 13 and 17, Vol. IV are out of print. 3. After indulging in gymnastic exercises, it is said that the hands can be kept in good condition by rubbing them with alcohol. M.J.A. AND H.S.D.--Your kind appreciation of the issue in question gives great pleasure to the publisher. There was no such number this year, in so far as the illuminated cover is concerned; but in the matter of stories, you will find that the contents of No. 5, of this volume, far surpass any other devoted to Christmas literature. It is full to the brim with good things well suited to the joyous season to which it is dedicated. ELECTRA.--1. If the directions for making electric motors presented in No. 3 are followed to the letter, you will be successful, but, if substitutions and alterations are made, the result will be that the apparatus will prove useless. 2. It is not at all likely that the company will interfere with the miniature telephone. 3. As the elements in a Bunsen battery are immersed in sulphuric and nitric acids, it would not he advisable to place it in a sleeping apartment. C. OGDEN.--1. There are forty-four States in the Union. 2. The famous River Nile is formed by the union of the Bahr-el-Abiad and the Bahr-el-Azrek. The first of these, or the true Nile, has its source in Lake Victoria Nyanza, and the second rises in Abyssinia. The Kagera and Shimiyu rivers, and the waters that descend from the plateaux from which rise the snowy peaks of Kenia and Kilimanjaro, unite to form that wonderful fresh-water lake, Victoria Nyanza, which covers an area of upwards of 40,000 square miles. W.F.S.--1. Minorcas, Hamburgs or Leghorns are the best laying fowls, while Plymouth Rocks, Wyandottes or Langshans are the best to raise for marketing purposes. 2. It will be found both cheaper and more satisfactory to buy ready-prepared mocking-bird food from a dealer in bird supplies or a druggist. The food for young mocking-birds should he meal and milk, and occasionally finely-minced fresh meat. Grasshoppers, spiders and meal-worms should be given to the old birds, together with a liberal supply of the prepared food. STUDENT.--Among the ancients, and during the earlier part of the middle ages, there was no distinction of capital and small letters. After the practice had been introduced of beginning books and chapters with large letters, often adorned or illustrated with artistic ability, it was not long before capital letters were employed in much the same way as at the present day. At times, however, their use was so extravagantly indulged in that many of the old books present a ludicrous appearance to the latter-day readers. The exact date at which they came to be universally used is unknown.